I think this review couldn’t come at a more relevant time. Why do I say that? Well there are some very big hints that the Astell & Kern AK120 is going to become discontinued due to the release of its direct successor, the AK120II, with only the other day Custom Cable offering an AK120 with a cradle, spare case, remote and 24/96 album for £600, that’s ½ the price of retail for just the AK120, not even including the additional accessories and I can imagine these stock clearances have started worldwide. So why would an AK120 review be even slightly relevant right now? Well because PWAudio in Hong Kong does a truly revolutionary modification to it, welcome to the PWAK120-B. You will not find the modification cheaper anywhere else that also includes a warranty  than with PWAudio, who charge 2500HKD (£188) for the modification and 1100HKD (£82) for their  balanced interconnect, along with the shipping fee to wherever you are. Red Wine Audio also do an identical mod, in fact they were the first company too do so (so credit is deserved there). The only real difference is the choice of cable used inside, with PWAudio choosing a crystal silver cable.

You have probably heard that the AK120 is a pretty good player on its own and you wouldn’t be wrong, it certainly can do a good job but this modification is for those who want the best. One of mine and many others a main complaint with the AK120 was that is just lacks some dynamics, how it doesn’t have the last say in details and how much it benefitted from an additional portable headphone amplifier. That being said it didn’t have a true line out, which is not ideal for those who plan on using it solely with an amp so you had yourself a catch 22. If you’re an AK120 user who uses an amp with it then this is the perfect mod for you and the same applies if you want a high end DAC in the tiny casing of the AK120.

With my Mezzo HiFi AK100

The mod does a few things and the first and in my mind most important change is how Peter Wong (owner of PWAudio) takes advantage of the dual Wolfson WM8740 DACs that the AK120 has and that is by removing them completely. Before you ask, YES, there is and advantage to that because the sockets for the WM8740 are pretty much identical (a few changes are made) to Wolfsons flagship DAC chip, the WM8741 and Peter fits two of them into the AK120. The WM8741 in a portable device is a big deal because it was a chip that was designed to and is in flagship desktop DACs and is well regarded for its minimum phase filter and elimination of pre ringing. Not only is this objectively a better DAC when it comes down too specifications but it is now configured to be run in hardware mode, so the software doesn’t get involved like it does in the stock AK120, and the minimal phase digital filter is manually selected. Expanding on the DAC running on hardware, it means we have no digital volume control any more, no headphone section, just a straight line out from the headphone jack. It doesn’t end there though because as the volume wheel loses a reason to exist, it is swapped into a Lemo balanced line out, for using with amps such as ALO RX Mk3B, Cypher Labs Duet and Ray Samuels Audio SR71B. So in summary we have WM8740 DACs replaced with WM8741 which now run in hardware mode, headphone stage is eliminated so portable amp has to be used with the added single ended 3.5mm line out and balanced Lemo line out.

The rather unique Lemo connector

Unfortunately we do still have one limiting factor from the AK120s software that does slightly limit the DACs and that is no native DSD. WM8740s can only convert DSD to PCM while WM8741s can do DSD conversions natively but because the firmware is set to put DSD straight into PCM, unless someone with the technical ability can make a firmware dedicated to this mod, we wont be seeing native DSD for it. Other than DSD though, just like a stock AK120, this can convert all PCM files up to 24/192!

The rest of the player remains pretty much the same to a stock AK120 as you would expect, with the exception of battery life that does take a hit here due to the much more power hungry DACs. Obviously battery life is dependent on the files your using due to how much processing power is used and with DSD we struggle to hit 4 hours while with redbook FLAC we can push 6 hours. I know it is not a lot but with me giving it a charge every night, it get through the days just fine.

Of course we then have the stuff that is already loved about the AK120, that beautiful sleek profile, one that stacks very nicely with amps and is very modern looking, especially with the included Italian Buttero leather case. You then have the MASSIVE memory capabilities, I have 128gb built in because I have the scratch proof titan version of the player and then you can build on that memory with the two micro SD card slots that both can accept 128gb cards, so yes, there is 384gb if you want. I will say that much memory does start a little bit of lag with the players UI, that is not the smoothest and does sometimes annoy, it isn’t anywhere near as polished as what the AK240 and its successor the AK120II has. You also have the other uses of it such as its ability to work as a USB and Optical DAC, which is actually very handy considering how stellar this is as a DAC, you may just end up using it as your home DAC with a full sized amplifier. It also still has the optical output for use with external DACs and it also does Bluetooth (not that I care). One of things I have always loved about the A&K series is their overall presentation and the way they are just a more pleasant experience and probably the most consumer orientated and polished “audiophile players” on the market.

So as I said this works as a portable transport and DAC but you have to pair it with your own amp and that can be portable or desktop, whatever you fancy. Obviously my main objective when doing this mod was to have a perfect portable reference, for both testing new portable amps and earphones and just getting the best sound on the go. I have used it with a real variety of amplifiers but I have moved into have two preferred ones for on the go. These are ALO RX MK3B and Vorzuge VorzAmp Pure. I like to use the ALO with stuff that’s a bit harder to drive such as my ZMF Headphones but I don’t like with my IEMs as it hisses a bit too much and that’s when the Vorzuge comes into play. With a beautifully silent background it gets on much better with my IEMs and lower impedance cans like the Beyerdynamic T5p! I do of course use other amps because while I love both of these amps, they don’t always have the right synergy with my headphones and I can the swap amps to my hearts content. It really is a benefit of not having the amp built in, your not stuck too that one amp sections sound signature of an all in one DAP.

With the Lime Ears LE3 and Vorzuge Vorzamp Pure. Cable on the Lime Ears is PWAudio Blackicon

Interconnect is from Mezzo HiFi

Obviously it has the potential to have whatever balanced and single ended output you could want with the 3.5mm line out being able to easily be transferred into RCA and the balanced output being able to be converted into any method of balanced connector although the only two used in balanced portable amps are the ALO/RSA Kobiconn connector (which PWAudio make an interconnect for) and iBasso’s Hirose connector (also possible). You could of course convert the outputs into a dual XLR feed but I have not been able to do that just yet unfortunately but if you sent PWAudio some XLR converters they would manage and the same applies if you sent Double Helix Cable the Lemo balanced connector.

With the ALO RX MK3B

Feeding my Beyerdynamic T5ps, which are balanced through a Double Helix Cable Molecule SE

Its funny because what was once a warm, mellow and musical player is now a precise, clear and very clean one. The DACs being switched really does change both sound signature and overall ability. We are playing with a DAP of a completely different caliber now, it didn’t take me long to be shocked by the revealing nature of the WM8741s, they throw so much detail at you and have such a high level of refinement, I guess they still have that in common with the original version. It wasn’t just a shiny toy syndrome initial shock either, its one that gets me on every listen, one that gives me a little grin, one that says I have done well here, one that says I shouldn’t have sound this good on the go and you know what, I love it. The DAC actually does have familiarities with the only other DAC I have with the WM8741s (Rein Audio X3-DAC), funnily enough. I guess that just some of Wolfson’s sound pushing through and these are very nice traits, they are a sound that is very resolving, very fluid and also very precise with timbre. The timbre could perhaps be a first hand positive from the minimum phase filters elimination of pre-ringing. See pre-ringing, is the small resonance an instrument or vocals makes slightly before it should actually become audible, its never a horrendous problem, one your probably rarely notice but its there and without it the timbre just seems more organic, it has a better decay and generally make a more impressionable impact.

With the wonderful Heir Audio IEM 8.0

There are differences with this and the Rein though and while they both feel like quite reserved DACs (more on that nature later) the Rein is certainly a more warm sound, not to unlike the stock AK120 signature. This is more balanced, perhaps with a little push up in the upper treble regions, not one that adds brightness but one that exaggerates clarity and extends on detail retrieval. The bass at the start is exceptional in all the areas of PRaT. Pace is pretty spot on, decay certainly doesn’t overhang with each note neatly separating itself if need be and with snappy rhythm. It has the extension needed that sits directly with the mid-bass and transits easily into the detail crazed midrange. Oh yes the midrange is balanced, full but not thick and just has abundance of microdetails, every little minute nuance is picked up, yes it shows flaws, it isn’t polite about them either but how else do you want it! Treble is crystal and very cut out but without jagged edges. It has good sparkle, great speed, very clarity driven and never ending extension too super human hearing ranges (AKA Batman).

Reserved? Hmmm, what am I getting at here? Well it’s the presentation of this, instead of it being right up in your grill, this are a bit further back. This does allow for a magnificent and broad soundstage with great depth and accurate imaging. The reserved nature did leave me with the feeling that dynamics could be just a bit more explosive when using with a desktop set up but I don’t know how much of that was too do with the poor quality 3.5mm to RCA cable I was using compared to the 3.5mm to 3.5mm and Lemo to Kobiconn interconnects I used with my portable amps only being of the highest quality and the dynamics being spot on.

Thing is throughout me talking about the sound quality parts of this review I have been as critical as I would a desktop DAC, one that needs pains power and would take some elbow grease to lift, not one that you can pop into your shirt pocket, charge over night and have on you in the middle of the dessert and still get beautiful music.

For some people the fairly low battery life, lack of search function or the need for an external amp is all more than enough to put you off. For me these are okay, I rarely use the battery all up even if others outdo it, okay the lack of search function is quite a tragedy really but having to use an amp is actually one of my favourite things, it adds to the versatility, I can no longer plug headphones straight in but with a range of different portable amplifiers, I can have it as the start of a rig that will drive any headphones I own, however sensitive or however inefficient. It also is very interesting, seeing how both different amps synergies with the PWAK120-B and then how they synergies with your earphones on top of that but whatever amp I am using, I know that I am using one amazing DAC.

A&K are making the classiest DAPs at the moment but they aren’t getting everything right on their own and with the help of PWAudio, you have the true ULTIMATE DAP, if sound qualities your thing anyway, yes the AK240 does have an upper hand on UI but that’s something that is always going to come in second for me. So what do I suggest you do? Go grab a AK120 now that they are at giveaway prices, either from a retailer in the UK like Custom Cable or even from somewhere like E-Earphone in Japan where they sell second hand pieces for dirt cheap (PWAudio can order them in for you, mod and then ship the finished product too you) and then send them on their way to Hong Kong so Peter Wong can turn them into this magical device, a device that will long outlive the already outdated stock AK120.

Sonny Trigg