Sony PHA-1 iDevice DAC and headphone amp in Review

About two months ago, the particulars of the Sony PHA-1 were leaked to the internet. About the same time, I suffered the second of what would become three intense bouts with an active stomach ulcer. In my circles, both made news. I’d would have to set up endless appointments with doctors that would cancel trips, meals, would-be drunken stumbling along busy Japanese streets; more importantly, however, the world of high-end portable audio had hit the mainstream. Sony stepped into the ring.

Wolfson WM8740 DAC
Sampling rate: USB DAC input: 24bit/96kHz
Frequency response: 10Hz – 100kHz (analogue audio input)
Maximum output power: 175mW + 175mW (8Ω); 26mW + 26mW (300Ω)
Impedance range: 8Ω – 600Ω
Inputs: 3,5mm stereo plug, micro USB (PC), USB (iDevice)
Outputs: 3,5 stereo plug (TRS type)
Battery: 3,7V Lithium Ion
Charge time: ~4,5 hours
Playback time: ~10 hours (analogue input), ~5 hours (iPod, iPad, iPhone)

Price in Japan: Â¥32.800 – 40.000Â¥ (~400$-520$)

Build Quality
I am the typical portable audiophile (aka marketing sucker). I’ve been a Sony user since the mid 1990s. Cassette Walkman, CD Walkman, MD Walkman, ATRAC Walkman, MP3 Walkman, plus various microphones and headphones. So when I say that I didn’t have a lot of faith that Sony could build something robust, take a look at my geek CV above. Apart from their microphones, which are veritable jewellery tanks, many Walkman products left a LOT to be desired next to the competition. Treating Sony stuff with kiddy gloves is something I got used to until their MP3 Walkmans, which were a good step up, but one that still didn’t match Apple by any stretch of the imagination.

But the PHA-1 is different. Gone are kludgy seams and paper-thin-and-easily-dent-able alloys of previous models. This machine is thoroughly designed to withstand the rigours of a portable’s life.

Check this:

Fenders around the volume pot and in/out ports, rubber guard rails, rear bumpers and countersunk screws. As far as I am aware, there is no other portable amplifier that has sports as many precautionary measures. It’s like Sony’s engineers got sick and tired of kitsch and decided finally, and at the very least, on top quality engineering.

Their one oversight is the USB input. The larger one sits too far into the case to receive support from the amp’s aluminium walls. I predict Sony will have to service a number of PHA-1 units for faulty and/or broken USB input. The micro USB port fairs a little better, sporting fingers that – just barely – wedge against the case for support. This oversight isn’t small. As the PHA-1 will primarily be used as an on-the-go DAC where primary input will be USB, it needs to be fortified against bumps and bruises that invariably will occur at the hands of purses, crowded trains, audiophile holsters, and over-large cables. This is failure one.

Apart from that – rather large nit – this amp is simply astonishing. Japan has long been praised for its machine precision (hell, in Japan machines build machines). Every seam, every groove, every angle is flush, tight, and proud. There is no flex in the case and no hint of rebellion anywhere. Even the rubber feet stay firm despite my most vigorous and violent attacks.

Ergonomics and Polish
This tight, flush, and proud build quality is fleshed out in perhaps the most polished of designs I’ve set eyes on. Sony thought of everything. Firstly (and tirelessly), I’ll start in on the rubber feet. The PHA-1 feet are a departure from the stick-on-warts that come with the amps of many other makers. Its feet are built into the chassis. They slip in on rails built into the outer case. These won’t go anywhere. They cover the top and bottom sides of the amp, making sure it won’t surreptitiously slip off a desk or out of a pocket. These are the PHA-1’s first line of defence.

The second, the massive front and rear fenders, is more obvious. Guarding against accidental volume increases and potentially fatal drops, these things have to be massive. They’re like a roll cage over a dune buggy, headgear on a teenager, a racing cage on a Polar Bottle. Hot damn! The volume pot moves effortlessly, and doubles as the on/off switch. It clicks into position at about 8:50 o’clock and runs to about 5:25 where there is a hard stop. There is no wobble, no off-axis spin, no grind. It is perfect. Turn it on to use the amp, and off to charge (when plugged in, that is).

Next to it, the input and output ports come in countersunk craters that accept large cables just as well as ALO’s fantastic The National and Continental amps do. You don’t have to turn the amp around to see whether or not it is charging. Both charge and power lamps are inoffensive. They are small and flush with the case.

Around the back, Sony array the digital inputs much like Qables do, even including a familiar input switch. ‘Audio In’ refers to the analogue input on the front of the amp; ‘Digital In’ refers to the two USB inputs. Again, the larger of the two is for iDevices, while the micro input is for Android devices and PCs.

Sony also include hooked elastic tongues to secure your source to the PHA-1. I had to dig into the manual for a hint at how to use them. The hooks bite into the PHA-1’s large shoulders, stretch across your iPhone, and across the amp to the other side, where again, they bite into the opposite shoulder. Brilliant. This design works great for securing your device in a holster, or on a desk. If you tend to use your amps from inside a pocket, you may want to consider using ALO’s excellent elastic bands instead, as the hooks may come undone (cue Duran Duran).

Even the packaging is a step up above the norm. Until now, portable amps and DACs have been the realm of fanatic audio makers who moonlight as customer survey designers. There are some exceptions, notably ALO who design simple and useful packaging and amps. On the other extreme, you have Jaben who haphazardly cram products into tight spaces and call it a day.

Sony are as Japanese as makers come. That means you get lots of packaging, plastic bags, instruction manuals – it’s a geek’s wet dream of reading material and openables. Yee haw. It also feels (for the first time) like the sort of package you’d see at a local ONOFF or Best Buy. Make of that what you will. Sony’s intention – I’m extrapolating here – is to have the PHA-1 in regular Jane stores catching the eye of regular Jane. It will be in retail stores all over, and in its font-happy package, innocuously blend into iDevice/PC peripheral fauna.

While esoteric, it doesn’t awe or confuse customers out of its periphery.

And while I’ve left the volume pot for last, it is by no mean least. It is the most precisely machined pot I’ve used, turning unctuously. Overall, there isn’t a portable amp unit that polishes up as nicely as Sony’s latest. If Leica decided on entering the amp business, they’d likely source from Sony.

A DAC merely converts your digital music into analogue signal. The PHA-1 can be used as a regular ‘ol headphone amp by plugging an analogue output into its AUDIO IN port. But, it really begs to be used digitally. Plug your computer into the micro USB port or your iDevice to the USB port, select the source on the rear of the unit, and play. It is an elegant solution in overcoming horrible computer audio, or augmenting your iDevice (or particular Android phone) with the clarity and power that only a good DAC/headphone amp can bring.

And Sony’s is a good DAC. It resolves music far better than your computer and, and in most categories, better than the best iDevice can at loud volumes. For all-out quality, the Cypher Labs AlgoRhythm SOLO is still king (by a good margin), but requires an external amp. The PHA-1 spits forth great quality and culls requisite boxes to a minimum.

All you need is the PHA-1 and the PHA-1 is all you need.

Unlike the SOLO (a straight DAC with line and digital outputs) and Venturecraft’s Unit 4.0 and Go-DAP X, the PHA-1 is strictly for headphone use. Few serious users will seriously consider connecting it to downstream equipment. The only output is an amped headphone signal. It’s good, but it’s not what you want to (or can) hook up to your preamp or external DAC without attracting the ire of the audiophile gods.


The PHA-1 really is a simple device. It sports two digital inputs, accessible at the back via the two USB ports, and one analogue in, accessible from the front panel. This arrangement is perfect for a variety of devices. All your audio are belong to Sony.

Having the analogue input along the front makes the PHA-1 very simple to use for people who either don’t have a compatible device or don’t want to use the PHA-1‘s digital output. Of course, the main selling point of the PHA-1 is its DAC. Otherwise, the PHA-1 is merely a very expensive amp.

And, because it can be charged and used by USB devices, you never need to carry around another cable or adapter. That is a major plus. In fact, looking at the CLAS next to the Sony will make your ears itch.

Sony’s latest amp also features a solid gain switch that changes input by about 3 decibels. This is especially handy when you switch between various earphones and headphones.

Again, it lacks a line output of any sort. You can of course connect it to analogue inputs via an adapter of your choice, but it is possible that the output will carry some artefacts not found in a true line level output.

Perhaps the PHA-1’s most amazing feature – especially for earphone users – is its absolutely black background. Well, eliminating all hiss and dirt from an amped signal is impossible. But Sony got as close as possible to a squeaky clean signal. Compared even to the impressively pious GoVibe Vestamp’s headphone output, it is angelic. The only amp I’ve tried that even comes close is the Headamp Pico Slim, which is made expressly for earphones and in-ear monitors. Damn.

Which leads us to sound.

Sound Performance – the Good
Black background – I could rant and rave all evening about the PHA-1’s black background. It is not something I’m used to doing. Sony’s engineers are quite proud of their achievements – and they should be: for a long spell, earphones were getting easy-to-drive. Some, like the Grado GR8, even run over 100 Ω, presenting very little load to an amplifier. Bless the gods of the moving armature. But, in 2011, the resurgence in balanced armature earphones (fuelled in no small part by Sony) pushed sensitivity levels back up while upping effective load.

Such sensitive earphones can show noise in even the best of audio hardware- that is, until today. The PHA-1 is as dead silent as portable headphone amps get. There is nothing on my desk now, nor ever, that compared. I suspect there will not be a comparable amp for some time.

Hands down, I can recommend it for users of SHURE SE530, Westone UM2, Sleek Audio CT7, the FitEar Private 333, and so on.

Benevolent volume pot – The PHA-1 also has a volume pot that makes perfect use of its Stygian background. Even users of sensitive earphones will find the right volume without blasting their ears off. Effectively, usable volume travel of the pot is just about 100%, depending on your headphones/earphones and volume. I don’t suggest going that loud, however, as the PHA-1, despite its delicate tramplings, still packs a punch.

Distortion and resolution – Almost across the board, the PHA-1 performs like a champ. I’ve used a drove of different ‘phones with it and nary a skip nor a blip hits its signal. Generally, contrast between frequency bands is stunning. This amounts to one of the most coherent sound images I’ve heard, where the smallest of details turn out in the music. Thanks in no small part to its nearly noiseless headphone output, this dune buggy simply rolls over your tunes. Rendered in particular beauty and absolutely clean lines is a favourite, Mozart’s Symphony No. 42 in F. The PHA-1 is equally suited to faster paced recordings, but this brilliant composition stresses in its sometimes airy, sometimes busy passages how capable Sony’s amp/DAC really is.

Stereo separation – Generally speaking, the stereo image of any amp takes a hit when under load. The PHA-1, like many amps, finds the load of low Ω earphones/headphones restrictive. Among all of my earphones, I found the Grado GR8 to be the most suited. The difference between the PHA-1 loaded by the GR8 and by the Earsonics SM2, for example, isn’t so stark as it is eye-opening. When presented indifferent loads, its stereo image is capacious. I suggest throwing something like the Beyerdynamic DT880 250Ω or 600Ω at the PHA-1 like you would throw the Autobahn at a BMW M3. You’ll feel better for it.

Noise – As mentioned above, there is next to no background noise in the signal. Not only that, but the signal to noise ratio is very very high, reaching almost to the idealistic lofts of 16bit limits. With the right headphones/earphones, this, too, causes detail to simply shine.

Sound performance – the Not So Good
High Ω headphone output – While by no means a Sony problem alone, it is an annoying issue to endlessly drone on about in portable amplifiers that should target the hardest to drive earphones instead of the easiest. Amps that target easy to drive earphones end up in many cases performing no better than the device they are meant to augment.

Sony’s new XBA line is exquisite. It is also incredibly sensitive and boasts a couple low Ω models. In order to wrest the last iota of resolution from their earphones, Sony would need an output of less than 1 Ω. And, being that the PHA-1 comes with a battery and without hiss, it sure seems targeted toward IEM users. Suffice it to say that Sony provided all of the tools necessary to dredge every detail from your music, but forgot the bond. In practical terms, the impact isn’t huge, but what is via the DT880, a continent-sized soundstage, bristling with low and mid range resolution, erupts into a less extravagant island, brilliantly laid out, but lacking in breathing room. If you happen to have an earphone that trips up the PHA-1, get ready for vocals drift more toward the pianos and violins that bang heads with the guitars. Again, Sony’s implementation of the amp is pretty good. Most amps on the market to day do much worse.

There is also the issue of truncated high frequencies, which rears a mostly pardonable head when driving earphones like the Earsonics SM2. I found that with earphones of less than 40Ω, treble truncation is pretty common. Bass and midrange remain unaffected, as do noise levels and the contrast between frequencies.

Overall, there is very little to complain about; I pick nits only because as a reviewer, I am sort of expected to. What good would it do to heap praises only on a company like Sony? None, I’m sure. I’m also sure that Sony are listening intently to reviewers now. A little tweaking and the PHA-1 could be the best of its kind on the market. Thus, I’ll stick with the assertion: the output impedance is too high.

Sound Qualities
Now, thanks to the tanning I received from many years of using what I honestly consider inferior Sony MD players and Walkmans, I wasn’t prepared for what I heard first from the PHA-1. Not at all.

I always start my listening with sensitive earphones; its pathological and I won’t stand to be cured. Earphones the likes of the SM2, you see, draw out an amp’s weaknesses, and being the bastard – in the figurative sense – that I am, I like to start with the bad news. The problem is that if there is bad news, I don’t get the right impression from the get go. Well, the SM2 is the PHA-1’s nemesis, but still, it is handled fairly well, exercising control, dynamics, contrast, and spitting absolutely no noise from its transducers.

Assuming you have the magical combination of a plus-40Ω earphone/headphone, you are in for clarity, that for all its resolution and dynamics, is beautiful. In particular, the oft-smushed toms and snares of a drum kit are absolutely pristine. Dare I say ‘spacious’? I do.


The PHA-1 renders drums and the space between drums in cavernous syllables. It just takes the right output device. Even with earphones like the SM2, or the ‘nemesis’ as I like to call it, contrast and space between instruments remain tip top. It’s just that everything else is pulled in closer together.

I’ve been able to detect no low or high frequency roll offs, though, again, with the SM2, highs rise a couple of steps above where the should be. It’s addictive in its own right.

Best headphones for the PHA-1
I reckon that doubters will come out of the woodworks when I say that the DT880 600Ω truly is, with certain genres, a wonderful tool to pair with the PHA-1. Provisos exist for every maxim. Both the Sony and the Beyer come from detailed, highly-resolving parents. If your music is extremely energetic in the high registers, you might find that the pair excite excessively. Favourable genres are trance, IDM, and classical. But a finer pair is the timeless HD600 or HD580 (if you can get hands on a pair). Don’t be scared off by their high Ω and relatively low sensitivity ratings, these headphones are powered mightily by the PHA-1. For me, comfortable listening levels for the DT880 are on low gain at up to 3 o’clock, or high gain at 1 o’clock. Turning all the way to 5:25 renders no phase errors or other audible artefacts.

Fans of organic, but detailed sound will likely love the Victor FX700 and FX500 paired with the PHA-1. It’s a practical match: Sony delivering the controlled resolution, the Victor delivering the bass and tasteful texture to the music.

Another favourite is Sony’s own XBA-3SL. I’m also partial to the pairing of Grado’s GR8 or the Ortofon e-Q5 with the PHA-1, which offers the best of the both resolution and impact and PRAT.

As mentioned above, the rear iDevice USB port is flimsy. Sony aught to fortify the back of the case. As a portable audiophile, I can assure from first-hand experience, that portable amps take much more abuse than they should. Starting with a foolproof design makes all the difference in the world.

The last (and most tirelessly droned on about) is the high Ω headphone output. Sony: it’s not for me, it’s for you. Lower that output and suddenly, you have one of the highest if not the highest performing all-in-one unit on the market. Thank you!

After nearly 3500 words, there’s little left to say but “wow”. Sony’s first step into the ring is a decisive one. Without directly stepping on any of their competitor’s toes, they battle close and hard against the likes of Fostex, Cypher Labs, and Venturecraft. The PHA-1 has a better internal amp than the Venturecraft units do and its DAC has no ‘quirks’ to shift around. Apart from its high Ω headphone output, and my bloody stomach ulcer, all is pleasure and light. If only Sony would fix that output, I could pop in my favourite amp-killing earphones, guzzle some pain meds, and be off to glorious sleep. Until then, I’ll balance proper headphones from the ends of one of the finest all-in-one units on the market today. Sony, I love you.

No hiss
Incredible dynamic range
Generally great performance
Almost perfect build quality
Ergonomic to a tee
Easy to use

High Ω headphone output
Non-anchored iDevice USB socket

Hot damn! Headphones really are a rockin’ way to enjoy music, right? Feel free to explore TMA’s headphone oubliette

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