a short diary of some part of my life.

Posts tagged Head-Fi

Office Headphone Setup

CEntrance is one of the few companies who offers driverless USB audio. They are not some companies who commission someone to make a product for them and label it as their own or a company who sells mostly overly hyped products that do not perform anywhere close to the high price tag, typically found on boutique brands. They are a design-engineering-driven company.


A lot of geekery trends were made mainstream by geeks and nerds. Geeks tend to be curious at new techs. Some of the techs are not necessarily ready for consumers but they still buy them. Thankfully, early adopters are now becoming public-beta-testers for those techs. A lot of bugs will be fixed, revised or even redesigned by the time the tech reaches mass-market.

In the early days of USB DAC, everybody did not seem to mind installing, maintaining, and updating drivers. Now, we want driverless solution. USB DAC solutions have matured to the point where we no longer have to tinker to use them. It’s now plug and play (on Macs).


Ever since I saw DACport for the first time, shortly after it is announced, I immediately felt this is the gear that I should try (partly because CEntrance is the maker). Normally, I don’t buy the first runs, I want to buy a gear that has been publicly tested. So, I purchased it. Long story short, it performs like a champ since day one. It’s been what? 3 years since its introduction and I hardly found anyone having problem with it.

Design Philosophy

Unlike many audio gear makers, CEntrance tries to keep much of the heavy-lifting to the gears they are making. Things like clean power, the need of isolated ground, ’boutique cables’, superb S/PDIF signal are not issues users must provide. They are actually helping us not worrying about those things and let us enjoy what really matters, which is good music, really. They are also not some random companies (some of them are quite famous) who sell half-baked gears.

As NwAvGuy wrote:
I completely agree some products are hastily thrown together using trendy components, made to look high-end, and rushed to market in search of quick profits. Other companies, like Centrance, take a much more holistic approach and put genuine high-end performance ahead of aesthetics and time-to-market. The quality of such products is more than skin deep and they pay a lot more attention to getting the normally hidden details correct.

Sound Quality

As what I have written about NuForce uDAC-2, the DACport is the better product. But not by a wide margin. It’s definitely better in every area. Compared to the uDAC-2, I can immediately hear a sense of speed, space, precision, and airiness. You don’t feel constrained with little guy. I’m accustomed to great bass slams (quality, not quantity), DACport will give you that.

It’s a refinement of what the uDAC-2 should have been. I think it’s either Nuforce got lucky or improvements in audio is really that small. Either way, this is the benchmark of a USB powered USB-DAC. This will be a classic or it already is.

Compared to a desktop amp, say a Schiit Lyr (w/ stock tubes), DACport excels in a few areas like speed and airiness. When I’m out of the house, without my desktop amp, I don’t feel I need of anything more than the DACport. It doesn’t make me miss my Lyr. I’m perfectly fine without the Schiit amp. It is that good. And when I use it as a DAC, it performs even better. A friend of mine who also owns a DACport run it as a DAC for his speaker setup claimed that he couldn’t differentiate his desktop DAC and his DACport. Too good? Maybe. But I have heard quite a few people whose experiences match my friend’s findings.

For IEM, the gain is too high for my taste. I like to listen in low volume range and it barely allows me to do that. Fortunately, unlike many portable DAC/amp, this one does not suffer from channel imbalance. There is zero detectable hiss at high volume range. I would like to have a bit more wiggle room to fine tune the volume for IEM. That’s the only con that I can think of.

For full size headphone, like my Grado RS1i, it’s a great match. Grado is notoriously known for its ‘smallish’ soundstage. Well, DACport fixes that. It doesn’t sound like many artificial soundstage inferior amps produce. Its sound placement and precision are just right where I want them to be. All the great traits about Grado house sound are retained and refined. Bass is deep and articulate. Micro-details are presented in a manner that does not pierce my ears.

I think this is the best portable DAC/amp in the market.

Build Quality

I consider my HeadAmp Pico to be the best in class in term of build quality in portable amp/dac world. That remains true with the intro of DACport. There are slight misalignments here and there on the DACport but nothing worries me. The finish is also better on the Pico. But Pico is the best, to be fair without a comparison with Pico, DACport is still miles better than the rest of the competitors. Have you ever seen any iBasso amps? If you haven’t seen one, if DACport gets 10-point, iBasso gets 6-point. Don’t even think about looking inside, iBasso gets an even lower score. Pico and DACport are engineering marvel. Look now, my uDAC-2 is already dead and it’s only been 3 years. I expect DACport to last for a long time, maybe not as long as my home gears due to the stress it often gets from frequent travels.

The Highest Recommendation

This is it, look no further. You don’t need to follow the trend. New products will keep coming but DACport will still be one of the best. There are not many companies out there who have the resource and expertise to compete directly with CEntrance. This is purely them outmuscling the competitors. They set a benchmark of what a portable amp/DAC should be.

I have had my eyes set on one of Schiit products for some time. Jason Stoddard and Mike Moffat are incredible engineers and their products speak for themselves. They are also a company that I must keep an eye on. I can learn a lot from them. Look at their branding and website, they’re hilariously funny!

Before I got the Lyr, I was searching for a HeadAmp Gilmore Lite, an AMB M3 or a HeadAmp GS-1. I have had a fair share with various amps, this will be my last, so this has to be really good. I like small amps. I don’t think a single-ended headphone amp needs a big enclosure; most of them are empty space anyway. On the other hand, I also want a tube amp badly, whether it’s on the output, the input or both. I made my choice to have a tube amp due to its ability to fine tune the sound by swapping the tube valves. And there is something magical about tube valves, its glow, its sound, beauty of the past.

Honestly, at first I didn’t expect the sound to be this good, nor the chassis or the build quality.

The usual setup:
Source: MacBook Air (w/ BitPerfect or Audirvana Plus playing mostly ‘good’ music ripped from CD or downloaded from HDtracks & iTunes)
DAC: CEntrance DACport
Amp: Schiit Lyr (various tubes – see below)
Headphones: Grado RS1i

(w/ stock tubes)

The Sound

So, the sound… It’s fairly transparent to the source. If an inferior source (NuForce uDAC-2) is used, it will sound bad. If paired with the excellent Wyred 4 Sound DAC-2, it sings. It drives my Grado RS1i (my only full-size headphones) with prowess and confidence. There are tons of power reserve left. I don’t have the chance on trying out an ortho with it. When I do, I’ll post an update here. The RS1i is an efficient headphones. Efficient is strange sometimes. Sometimes, when you put more power to it, it doesn’t sound any better. I suspect what Schiit is giving it is not merely more power but finesse that most inferior amps lack. Low level listening session suddenly becomes enjoyable.

Keep in mind that if you are planning on pairing a Lyr with sub-par DAC, forget it, it won’t perform. The amp will perform at its best when paired with a superb DAC. And just like the importance of a great-sounding DAC, it’s even more important to get the best headphones that you can afford. Get a pair of headphones first, then a DAC and an amp. While the Lyr can perform well when fed with great source, it’s not as transparent as I would like. I want it to be a little more detailed and produce a bit more immediacy. The soundstage is also a bit constrained and not as airy as some of the best single-ended amp (tube and solid state) that I have tried. I guess tube-rolling will definitely help here. This is the real hassle of having a tube amp, most of the time, they won’t perform at their best with stock tubes.

I never have any problems with hum or noise. My Lyr is dead-silent, even when I turn up the volume. If you have hum/excessive noise problems, check your electricity. You might want to consider getting some sort of a power conditioner or an isolation transformer.

Build Quality

That’s enough for the sound. What about the build quality? Have you ever owned an amp that is produced by one of the well-known headphone amp manufacturers that uses aluminum for its entire chassis? If you have, say a Woo Audio amp, the Schiit Lyr (and all Schiit products) has a much better build. All screws are well positioned and fastened. Woo finishes look sloppy at best. I don’t think Schiit will let the kind of sloppy fit and finish as Woo amps have passes QC. It is that good. To be fair, Woo Audio chassis finishes do look bad (I have owned a few Woo Audio amps). What about its PCB, fitment, soldering job? It’s just as good as or better than the most well-built electronics out there. Schiit’s overall build quality is up there comparable with high-quality well-known brands, thousand of dollars gears. I think this is a testament how much Schiit cares about their products. And I’m sure it will easily last a lifetime or more.

The only design flaw that I can think of is the tubes are seated deep into the chassis which make them really hard to remove. Use a piece of masking tape to pull the tubes.

Superb Product

Please don’t judge it by the price. Price does not always equate with quality. Try it, give it some time to warm up and you will be rewarded by the great sound it produces. They spent a bit of time explaining why achieving the price they offer is actually possible. I think this is the ultimate single-ended headphone amp. I’ll be following Schiit, they will be around for some time, producing yet another bombastic line of products.

(for tube rollers) stop here if all you want to use is stock tubes.
This section will be updated as I get more tubes.

stock (GE 6BZ7) Vs. JJ
forget it, waste of money

stock Vs. 1963 Telefunken 6DJ8
coming soon

stock Vs. JAN Phillips 6922
coming soon

stock Vs. NOS 6N1P Russian (Valhalla’s)
coming soon

stock Vs. Amperex 6DJ8
The most detailed so far…

stock Vs. Siemens 6922
coming soon

stock Vs. Mullard CV2492
This are the tubes to get if you want to turn the Lyr to lush-sounding tube amp…
I’m liking the Mullard. They are my fav…


Like everything else, a journey may end at some point. I just didn’t expect this would end so soon. I was an advocate Head-Fi reader – not a frequent poster. I have gradually but surely, walking away from Head-Fi. It has become a place where I buy and sell my headphone gear. There are only very few respected Head-Fi members whose comments/replies are worth reading. To make it even worse, most if not all of them are Head-Case members (they provides better users’ impressions due to their vast knowledge about audio electronics in general and anti-hype approach). Head-Fi user interface has also become dreadful (did I mention that Head-Case interface is MUCH better than Head-Fi’s?). A prominent Head-Fi member have summed up the problems, he too decided to leave.

Head-Fi’s Major Issues

There are many other major (disturbing) issues that prompted me to say good-bye. Issues like their over-protective approach over their site sponsors, post deleted without any notice (I have seen this myself, several times. I refreshed the page after 5 minutes and some posts were gone), users’ idiocies (of defending their purchases, users’ incompetencies… make the forum very uninformative, unfriendly, and useless. There is another issue (another issue and another issue?) about sponsors trying to make easy money. Head-Fi is going to be a much worse place for those who cheer good sound if the admins decide not to do anything about those issues. Many have left, many have not posted useful posts for some time.

Head-Fi DGAF about Regular Folks

Even after issues after issues are exposed, Head-Fi still do not give a crap about us regular folks who spend countless hours on honest jobs. If I were to run a forum, read by millions of unique visitors per month like Head-Fi, I would make sure that the vendors are always kept in check, especially after vendors are caught lying or making very questionable products at extraorbitant price. They could have made the forum much safer for users with a bit more effort but they don’t.

It’s not fair to leave without saying anything, so here is a few bits of my story:
During my time searching for the right headphone, amps, and sources, I have learnt a lot. This headphone journey led me to speakers system which I think sounds superior to any headphone systems on the planet. I’m grateful for my experiences on Head-Fi. Without it, I would not know how to start looking for the right system. For those who have the funds, the space, and the time to set up a speaker system, but you are still using headphones, I urge you to try a good speaker system. It will blow you away!

I figured, it will be fair to list what headphones and amps that I have owned and tried. So, you’ll know how far I have gone. Here are the lists:


  • JH Audio JH16 Pro
  • Sennheiser HD650
  • Sennheiser HD800
  • Grado RS2i
  • Grado HF2
  • Audeze LCD-2 Rev.1
  • Beyerdynamic T1
  • HiFiMan HE-5
  • HiFiMan HE-6
  • Shure SE535
  • Grado HP2
  • Sennheiser HD600


I think I have had a few more amps but I can’t remember the names.

Which headphone and headphone amp are the best and the worst?

From the owned lists above, I consider Audeze’s LCD-2 and AMB B22 as the best headphone and the best amp. The worst are Sennheiser HD800 and Audio-gd Phoenix. Although I did not own them all at the same time, I can definately tell you that HD800 and Phoenix are my least favorite headphone and headphone amp.

I dislike HD800 due to its’ artificial-like sound signature. Anything that comes out from HD800 do not sound right to me. Audio-gd Phoenix sounds too smooth, is not as transparent as other top-tier amps, and has its’ own sound signature. My only requirement for a good amp is complete transparency. Its’ sound signature masks almost everything and changes my source’s sound signature. A reference amp must be transparent to the source, otherwise, you are better off settled with a tube amp like I once did with a Woo Audio 6 SE. AMB B22 and HeadAmp GS-X are much better amps than Audio-gd Phoenix, they are much more dynamic and transparent. I can easily do DBT on what source is used with AMB B22 and HeadAmp GS-X but with Audio-gd Phoenix, the differences between sources are very subtle. Even with ACSS, the Phoenix sounds soft and dull compared to AMB B22. I’m beginning to think, Audio-gd is not good at designing headphone amps. I have also briefly auditioned their Compass and C-2C and found them to be mediocre at best. A small headphone amp like AMB M^3 and HeadAmp Gilmore Lite are also much better alternatives than the big honking space heater Phoenix. Audez’e LCD-2 should pair well with any top tier amps like the GS-X. It is a very transparent headphone, I think it’s a better headphone than HiFiMan HE-6 which is quite piecing on the ears. I sold the LCD-2 because I simply wanted a retro headphone and I was also disappointed with LCD-2 build quality. It’s gone now and I don’t miss it at all.

Portable Amp (w/ DAC)

There are a few things that I want to talk about portable amps. If you really need portability and you are using a notebook computer, look no further, get a CEntrance DACport. It has a superb DAC and a superb Class A amp for its size. Don’t bother buying portable DAC/amp from various unproven manufacturers, they are all inferior. Most general DAC/amp combo use battery and they need to be recharged. This is not the case with DACport, DACport only needs a USB cable to connect it to your laptop or your iPad because it does not have a battery. It draws its power from your computer’s USB port. You don’t even need to install any driver. It’s that easy. Oh yes, you can use a DACport with an iPad. If you are using a portable music player, don’t bother buying a portable amp. It adds bulk and weight. You may also end up spending too much money on LODs, interconnects… Look at this set-up: Cypher Labs AlgoRhythm Solo. Honestly, I think it looks rather stupid. If I have to use a portable music player like an iPod, I greatly prefer to use my old trusty iPod Mini (that’s right, iPod Mini) without an external amp or DAC. Sometimes, audiophiles may turn into audiphools. They are willing to sacrifice everything for one thing called sound quality. I bet CEntrance DACport offers much better SQ than that bulky set. That bulky set is NOT a portable setup. Instead of wasting your hard-earned money for silly things like LODs for an external amp or DAC, get yourself a nice pair of headphone. You will be much more satisfied in the long run.

Do I keep any headphone and headphone amp?

Now, I’m settled with Schiit Asgard (3/16 /11 – oops, got a Lyr now, purely for the tubes) and Grado RS1i. I consider both of them to be the best in their price ranges. Surprisingly, I find Asgard superior to Audio-gd Phoenix (yep, a $250 made in USA amp Vs. $1200 made in China amp). Grado RS1i is a very fun pair of headphone. It excels with rocks. Guitar strings sound superb. It’s just magical with rock genre. The RS1i fits better on my head, LCD-2? not as good and very heavy. You may question why I decided to scale back a bit. Well, the reasons are:

  1. I no longer listen to headphone that much. I listen to headphone ± 1 hour a day.
  2. I don’t feel comfortable wearing headphone for hours.
  3. My fear of hearing impaired.
  4. Speakers are superior in every way. Headphone cannot resolve the same level of resolution and imaging as a good pair of speakers.
  5. I could have splashed a chunk more for a GS-1 which had always been my number one preference for a single ended solid state amp. It’s been well known that GS-1 and GS-X are the most transparent headphone amps in the market. My reason is simple, sometimes, good enough is good enough. Asgard Lyr is good enough. 😀

Now, I’m obviously a headphone lover, but the truth is, as much as I love headphones, they will always be secondary to speakers in my life, because speakers are just that much more dimensional, natural, and convenient to listen to; there’s nothing on your noggin that could fall off, or prevent you from hearing important audio cues like phones, doorbell, neighbor screaming for help, and it’s much easier to share music with others.

Schiit Asgard Lyr and Grado RS1i are my last headphone system. I will likely not going to add a headphone, unless it is broken. That Schiit amp will likely outlast me, so there you go, a long-lasting headphones system. And this is where I stopped: A Happy Ending (Hi-Fi) ~ [I also explained a bit about how you should spend your money, where to spend it on, and various issues about audiophile in general]

Head-Fi users’ impressions and reviews…
I think it will be wise for those of you who are reading reviews to make sure that the reviewer has considerable knowledge about various amps in the market. A review like this is pointless IMHO… The reviewer did not compare his gear with top-tier amps and DACs or even worse, the reviewer has little to no experience with top-tier amps and DACs. I imagine the reviewer will be completely floored with an AMB M^3 or a HeadAmp Gilmore Lite .

From those many reasons above: Head-Fi is no longer a useful place and headphones are inferior to speakers, I decided to leave Head-Fi world. It’s been a fun experience. Thank you Head-Fi!


Update (3/19/2011): ~ read links on the top of this page:
Looks like Head-Fi has become extremely hostile towards NwAvguy, links to his blog have been deleted. Let’s wait and see what will be deleted next… This is not the first time I have seen this happened on Head-Fi. I just didn’t expect them to be super protective of their sponsors. I have all the print screens and PDFs of the deleted posts if anyone wants to read them. No wonder there are more and more bad guys roaming free on Head-Fi. 😦 I guess, a farewell to Head-Fi is a good thing after all…

About two years after the introduction of the original Pico amp (with or without DAC), Justin introduced his latest creation, the Pico Slim. The new Pico Slim is primarily designed to drive IEMs (in ear monitors) ~ It’s not designed to cater larger portable amp market. It’s small and slim form factor is meant to attract those who want to carry a portable amp that doesn’t consume too much space. There are many portable amps in the market but none of them has the design prowesses or the form factor of the Pico Slim.

HeadAmp has been building their reputation based on their extreme attention to details and superior designs. Justin Wilson, the man who is running HeadAmp all by himself is one of the most respected headphone amp designer in the industry. HeadAmp is a one man shop. So, please bear with him if he has not replied your emails or phone calls.

I’m using the Pico Slim almost everyday. It’s small, err… it’s tiny…! It doesn’t add much foot print to my already large iPod 5.5G. There are portable amps that add their own sound signatures. It’s not necessarily a bad thing, I just prefer a more transparent amp. Unfortunately, most portable amps do have their own sound signature. Pico Slim is no exception. Given how bad the iPod is and channel imbalance issue in most amps, Pico Slim is a revelation. It is silent (silent in HeadAmp term means completely silent at any reasonable listening level; I can’t detect any audible noise at normal listening levels), more transparent than most portable amps and tiny. I ended up not liking my iPod 5.5G, it sounds congested if compared with the highly regarded AMB Gamma 2. This is a bit disappointing because the reason why I bought the Slim is to pair it with my iPod, now it’s also serving its’ duty as a transportable computer rig. In my experience, a separate DAC is always better than an iPod. Apart from being tiny, it’s a cute amp.

Although it has 255 steps attenuation, I find half of the volume range useless. I find myself always go pass 12 o’clock to get reasonable listening volume level. Finding the sweet spot is quite troublesome as well, I wish Justin could have made it to have fine volume adjustment throughout its’ volume pot. BTW, the sweet spot is somewhere around 1 o’clock. Oh and, the volume knob itself isn’t as sturdy as the original Pico. It feels quite fragile. Other than the volume control and the volume knob, I don’t have anything else to complain.

For those who care about the chassis work, it is simply the most gorgeous portable amp that I have seen. Justin has always amazed me with his work. This one is no exception, the chassis was milled from a single piece of aluminum, CNC cut, and laser engraved. Even the tiny volume knob is a solid aluminum.

If you are looking for a portable amp to drive your IEMs, this is it, the near-perfect portable amp.

Here are of Justin’s posts to get some glimpses on how he designed the Pico Slim:

I have not announced a price yet, but I have said it will be in line with my other portable amps – despite the much higher cost of parts of the Pico Slim, and time spent designing it. I would say it sounds a little warmer than the original Pico, but I am focusing on the experience of using this amp with IEMs and other sensitive headphones.

The prototype finished running with a battery life of 72 hours. That’s a significant increase from the original 40-50 hours, while the enclosure is also now 20% smaller. This isn’t due to changes in the circuit, it still uses the same amount of power, just changes to the layout that allowed a larger battery to fit. …

The battery pack will cut off automatically when the voltage gets too low, so I wouldn’t worry about that.
As for battery leakage, after about a year of non-use you can expect the charge to be about 2/3 full. 1 week without use is nothing
I really don’t think there’s much you can do to increase the life of the battery, so don’t worry about how you use it and charge it. They are rated for 500 cycles, which means the battery is expected to be at 70% of its original capacity after that usage. At 8 hours use per day, that would be 12 years. So that rating is only useful for devices like cell phones that might only have 2 hours of talk time, because batteries like this only last about 3 years whether you use them or not. All the MacBooks and iPhones have internal batteries and they are far more taxing on the batteries, and you can’t replace any of them easily. Hasn’t hurt their sales, so they don’t care. At least I’m honest about this and I’ve made it extremely easy for the battery to be changed. Remove 4 phillips screws, unplug battery, plug in new battery, put screws back in. That’s it. I guarantee to offer new batteries for at least 10 years, and beyond that there are hundreds of other battery cells that can fit. By that time the latest technology will probably get several hundred hours of life in a Pico Slim.

Noise level will be higher than the regular Pico. All digital volume controls add noise. But it’s insignificant and well worth the advantages. With ES3X, my most sensitive IEM, I can’t hear anything until it’s past the level I would ever want to listen at.

You are talking about the direction of the polishing. You’d have to polish forever to remove everything. The owner of the company that does this work has said I am the most demanding customer he has ever had, and that’s probably true. Many of the metal finishes on mass market electronics are created with processes that are illegal in the United States and most western countries as they are known to cause cancer or are very bad for the environment but they’re OK in China. This makes things more difficult. Accept that these are hand polished and may have small imperfections that would not be found with an aggressive chemical process.

The coupling caps are Niobium Oxide and PPS film.

It appears that the Pico Slim will be the only USB-charging headphone amp on the market that follows the rules for USB charging. A USB device must request permission from its host before charging. Charging can be done at up to 100mA or 500mA, or be denied any current such as when the computer is asleep. Most USB devices simply try to charge at 500mA at all times by “stealing” power from the USB port without permission. This is the cheap and easy way to do it. There are risks and problems with this. Risk of damaging a low power (100mA) USB port, or charging won’t work at all because the computer will shut down the USB port. While most new computers and full-size laptops only have high power (500mA) ports, low power ports are increasingly common in portable devices like netbooks, UMPCs, and PDAs that will have the ability to charge another device in this case a headphone amp. The Pico Slim will find out if the USB port is a low power (100mA) or high power (500mA), and then charge appropriately. This means it will be compatible with all USB ports and all devices that can act as a USB host. Find out if your USB charging amp does this, if not, you are risking damage to a computer/other host device, or you won’t be able to charge at all.

Clipping ~ Was looking at some specs last night and realized another area where the digital volume control in the Pico Slim does extremely well. It has the ability to accept audio inputs that are far larger voltage than the voltage that powers the digital volume control (in the case of a li-ion/li-poly battery, usually 3 to 4V). With most other digital volume controls, audio inputs at higher voltages than the battery voltage will be clipped. Does your source output more than 3-4 volts / 1-1.4Vrms? If you are using an iPod or other portable DAP, you should be OK — most of the time. If you use a home CD player or DAC, chances are you will be in the clipping range. Many USB DACs will also output above this level. Clipping will become a significant issue especially with recent CD pressings being made with almost no headroom. The Pico Slim can accept an input signal far greater than necessary from any kind of source.

the whole point of the digital volume control was because regular analog pots had poor left/right matching at low volumes, and they were also limited in how quiet they could go.  so with many IEMs, you could be at a listening level even with the volume knob all the way down.  turn it up slightly and it could be very loud, and still have left/right imbalance.  this way you have far more range.  about every 1 degree of rotation is a 0.5dB change.  sure you may find that leaves a 20 degree range with a particular headphone/source setup, but its going to be compatible with all combinations you throw at it, and you’re going to be able to hit every 0.5dB adjustment with slight turns of the knob.  the alternative would have been to have an infinitely rotating knob, which would have required resetting the volume to 0 at power off, and there was no room for any kind of display to indicate volume level.  I wanted to duplicate the experience of the analog pot, just with much more attenuation and way better channel matching.

THIS FEATURE HAS BEEN CANCELLED ~ Here are some ideas. These are all things that could be added later. Right now, the priority is just getting the Pico Slim finished. – Left/right balance adjustment. I have seen several people ask about this recently. It could be adjusted through the USB port. – Change the volume control. You probably don’t want to do this, since the Pico Slim already has 255 steps, 0.5dB between each one, and 110dB attenuation and nothing comes close to that kind of precision adjustment. But if you wanted to, you could change it so it only has 23 steps, and set it up so that it emulates a DACT Stepped Attenuator exactly. Or maybe you find even though the Pico Slim has so much adjustment, you still only ever use the area between 10-12 o’clock. Well you could customize it so that 10-12 o’clock becomes the entire 300 degree rotation of the volume control. – Scare your friends by making the volume go full blast 1 minute after power on. Not recommended. – Count the number of times the battery has been charged.

Here is a link to the “Q&A” about the Pico Slim that Justin posted on the original Pico Slim thread: HeadAmp Pico Slim portable headphone amplifier

I sold my Woo Audio 6 and bought myself an early Christmas present, a Woo Audio 6 SE (Special Edition).

It features a separate power supply unit which uses 5AR4 or 5U4G rectifier tube and an amplifier unit which uses 6DE7 or 6EW7 dual triodes power/drive tubes. The amplifier unit has two chokes per channel and utilizes direct interstage coupling design, there is no coupling capacitor in the signal path.

My first impression was OMG… this thing screams power, a lot more powerful than my old Woo Audio 6. I’m still trying to get used to the sound of the amp, the amp is surprisingly neutral and smooth. I guess it’s true about solid state being too analytical which is not my taste at all. I have also tried many different kind of musics and I have to say, WA6-SE makes them to sound as good as they possibly can. One thing I really like about the WA6SE is it allows me to enjoy low volume listening with full impact and detail – something I haven’t been able to achieve with other amps I’ve tried.

I have 11 sets of power/drive tubes and 8 sets of rectifier tubes. Fat bottles 6EW7 power/drive tubes seem to have wider soundstage but they also have less impact if compared to 6DE7s which are somewhat more musical. As for the rectifier, I have the excellent Emission Labs 5U4G Mesh, this is one beautiful tube, especially when it’s on. I notice the sonic signature changes to the better side. The changes are minor, bass is a little deeper and controlled, everything seem to be well balanced. I don’t recommend those who own WA6SE or any OPT tube amps to buy more expensive rectifiers unless they want to because of the tubes looks, the changes are minor to warrant the price differences. There are two beautiful rectifier tubes, the Sophia Electric Princess 274B Mesh and the EML 5U4G/274B Mesh. The SP 274B Mesh is just as beautiful as the EML Mesh tube, it’s not a true mesh plate though.

Although the amp has performed flawlessly since day one, I’d like to change a couple of things; the rectification needs to work perfectly, sometimes the rectifier tube emits flash, I’m very concern about it as I don’t want the PSU unit to shorten the life of the rectifier tube. I have a few of very expensive rectifier tubes and I’m very worried if the recent “bad batch” of the Sophia Electric Princess 274B mesh is not really a bad batch but is caused by the design of the PSU unit. I want to use 6FD7 tubes as they are my favorite tubes, I was told I must not use them but Woo Audio does not specify a reason for it. There is a fix posted on for it. The fix is simple, you just have to swap two 470uF/100V capacitors in the amp unit with two 470uF/200V capacitors (I choose Panasonic TS-ED for this application). I will work on it once I have time to play with my soldering iron. I will also swap the bypass caps (220uF/16V) with Black Gate N-series 470uF/16V. Hopefully new caps will improve the SQ. In the future, I may add additional power filter caps to filter out hum that I can hear with my Sennheiser IE8 (IEM – In Ears Monitor). I want the amp to be silent with any phones plugged into it.

So, there you go, a superb headphone tube amplifier that does not cost arms and legs.
Thanks Jack and Wu family, for making this beautiful amp.