Up to 84% in savings when you subscribe to The Absolute Sound
Logo Close Icon

Begin typing your search above and press return to search. Press Esc to cancel.

Sony PHA-2 DAC/ Headphone Amplifier

Sony PHA-2 DAC/ Headphone Amplifier

As part of its “high-resolution initiative” Sony has rolled out several exciting new products during the past year including the HAP-Z1ES and HAP-S1 digital players, the NW-F887 portable player (Asia only), and the PHA-2 portable DAC and headphone amplifier. I reviewed the HAP-Z1ES in Issue 241. It proved to be an outstanding value that has shaken up the digital-audio-player marketplace.

The Sony PHA-2 portable headphone amplifier and DAC was created to be a digital “bridge” product, designed to improve the sound from smartphones, iPods, iPads, and computer USB sources. For the on-the-go audiophile who wants to own and carry only one DAC/headphone amplifier on his travels, the Sony PHA-2 could be just what the traveler ordered.

A Tech Tour
The 270-gram (.6-pound) PHA-2 is housed in an aluminum enclosure that features a zinc alloy bumper as well as a unique rail/edge design. It has provisions for digital inputs from a PC via a micro-USB, or an iPad/iPhone/iPad via a standard USB, or a high-resolution-supported Walkman via Sony’s own proprietary mini-USB connector. The PHA-2 also accepts analog via a mini-stereo input that doubles as a line-level output. Outputs include one mini-stereo headphone output plus the line-level. One side of the PHA-2 has a pair of toggle switches to select between the line-level and headphone outputs and to choose the normal or high-gain amplifier-output levels.

Controls on the PHA-2 include a large volume knob, nestled underneath one of the alloy bumpers, that also turns the unit on and off. Next to the volume knob are two small LEDs. The “power” LED glows green when the unit is playing and also tells you the charge level of the internal rechargeable 3.7-volt 2160mAh Li-ion battery via a series of blinks when you initially turn it on. Three blinks signify a full charge, two a partial charge, and one blink means you don’t have much time before recharging will be needed. The other LED glows red during recharging.


Sony PHA-2 DAC/ Headphone Amplifier

On the bottom of the PHA-2 you’ll find three digital inputs as well as a small toggle to select which one is currently active. If you’re looking for a mute button or any way to navigate through a music library, you won’t find it on the PHA-2. Whether you’re using the PHA-2 as a DAC or as a headphone amplifier, Sony assumes that any device you hook up to the PHA-2 will have its own navigation and playback controls. During the review period I used the PHA-2 tethered to a variety of devices including an iPhone 5 (via direct-digital lightspeed-to-USB connector), the Astell&Kern AK100 (via the analog input), the Astell&Kern AK240 (via analog), and several of my Macs via micro-USB.

The PHA-2 DAC section supports a wide variety of digital formats including PCM up to 192/24, and DSD 2.8 (64x), and DSD 5.6 (128x) via any of its digital inputs. Sony’s technical literature notes that DSD 5.6 is not available for the Mac, and using Audirvana Plus 128x material is automatically converted to 176.24 PCM for playback. The PHA-2 employs an asynchronous USB 2.0 transfer mode that uses a proprietary driver for Windows; no drivers are needed for Mac.

Setup and Use
With all the portable and computer playback devices I tried with the PHA-2 setup was virtually plug-and-play. The only “tricky” part was selecting the right position for the PHA-2’s digital-input toggle switch. Occasionally, when going from DSD material to WAV on my Mac, I could “trick” the PHA-2 into spitting out noise instead of music. Resetting the audio preferences in Audirvana Plus quickly solved this minor glitch.

Battery life on the PHA-2 is spec’d from 7 to 15 hours. If used as a DAC/headphone amplifier the figure will be the lower number; if used solely as a headphone amplifier you can expect battery life to be closer to the 15-hour figure. Recharging the PHA-2 can only occur while it is not playing music. This means that if you use the PHA-2 as your PC’s DAC you need to turn the volume to “off” at the end of the day if you want to have a full charge for the next day’s playback. If you forget to turn the PHA-2 off, yet leave it attached to your PC, it will not automatically recharge overnight.

 

One clever ergonomic feature on the PHA-2 is the “rail” edges. These edges are for attaching two stretchy rubber straps that are designed to hold your playback device so it’s firmly connected to the PHA-2. I used the bands with the iPhone 5 as well as the Astell&Kern AK100. In both cases you end up with a fairly substantial mass that is too thick to fit in anything except a large cargo-pants pocket. Also, when you add the weight of the PHA-2 to your portable playback device, you are very likely to wind up with a package that weighs close to, and in some cases even more than, a pound.

If you want to use the PHA-2 as a DAC in a desktop system you’ll discover several minor ergonomic issues. First, with an analog source, such as the analog output from the Astell&Kern AK100, you will need to use the headphone rather than the analog-out to drive your preamp or powered speakers, since the analog output also doubles as the analog input. Also if you need two outputs, such as when you want to drive a set of speakers and a subwoofer, since the PHA-2 only gives you a single analog output you will have to split the signal in two via a jumper or Y connector, or get your amplifier/monitor-speaker feed via the pass-through from your subwoofer.

I used the PHA-2 with a variety of headphones from high-sensitivity models such as the Westone ES5 and Ultimate Ears IERM to more power-hungry cans such as the Audeze LCD-2, Mr. Speakers Alpha Dogs, and Beyer Dynamic DT-990 600-ohm version. With the Beyer Dynamic DT-990s headphones I did long for slightly more gain and volume when I listened to my own live concert recordings, even with the high-gain setting engaged. The Mr. Speakers Alpha Dogs and Audeze LCD-2 headphones had just enough gain to deliver satisfying volume levels with my own source material. With high-sensitivity in-ears, such as the Westone ES5, which exhibit hiss with many headphone amplifiers, the PHA-2 was dead silent with lots of gain, making it highly compatible portable with the ES5s.

If you are looking for a headphone amplifier to drive especially inefficient headphones, the PHA-2 should be auditioned to see if it will deliver adequate power. Some prospective owners will undoubtedly be disappointed that the PHA-2 can’t drive everything in their headphone arsenal, but in my experience finding one headphone amplifier that works equally well with all kinds of headphones is nearly impossible. A more reasonable goal is to find a headphone and headphone amplifier that have synergy together. For my uses the PHA-2 proved to be ideal with highly efficient headphones such as the Westone ES-5 and Ultimate Ears IERM, and certainly adequate with most medium-sensitivity cans. The new Oppo PM-1 headphone was an especially good match for the Sony PHA-2.


Sony PHA-2 DAC/ Headphone Amplifier

Sound
Since the primary reason for choosing the PHA-2 over other DAC/headphone amplifiers such as the ADL X1 is the PHA-2’s DSD capabilities, I spent a majority of my critical listening time playing my own live on-location DSD recordings through the PHA-2. One of my more recent recordings was done at a house concert in Boulder, CO, using a pair of Alesis/Groove Tube GT AM30 FET microphones with cardioid capsules to capture a performance by the mandolinist/clarinetist Andy Statman accompanied by Jim Whitney on acoustic bass. The microphones were set up approximately five feet away from Statman and Whitney in a coincident pattern. Statman’s spirited playing provided material with an extremely wide dynamic range as well as a rich harmonic palette. Listening with the PHA-2 tethered to my Ultimate Ear IREMs, which were the in-ear monitors I used while originally making the recording, I was instantly transported back to the moment the recording was made. It was as if I were listening to the live microphone feed. Even during Statman’s most frenetic and dynamic clarinet solos the PHA-2 never had the slightest feeling of stress or dynamic constriction.

On the audience’s applause between numbers the PHA-2 did a superb job of preserving all the subtle location cues as well as the not-so-subtle transients that clapping hands create. Frequency extension and tonal accuracy through the PHA-2 were especially good on Whitney’s acoustic bass. I could hear not only the transient pulse of his plucked notes, but also the way the acoustic bass bloomed as the notes spread through the room.

When I switched to using the PHA-2 as a DAC/preamp connected directly to an April Music Eximus S-1 power amplifier driving a pair of Audience Clair Audient 1+1 speakers in a nearfield setup, I was once more impressed by the PHA-2’s sonic abilities. All the dimensional and locational cues were preserved accurately by the PHA-2. I could even tell when Statman pointed his instrument in a slightly different direction, from the way the room’s reverberation and bloom changed. When Statman switched to mandolin all of his characteristic contrapuntal humming could be clearly heard and located in space, several inches above his mandolin. The PHA-2 also preserved the differences in room reverberance and bloom between Statman’s voice and his mandolin.

Since many prospective owners will be using the PHA-2 with smartphones, I spent some time near the end of the review period with the PHA-2 tethered to my iPhone 5 via its digital lightning connector. Using several high-definition Internet radio stations as primary sources I was impressed by how involving and musical the results were. Using the “HiDef Radio” app I listened to the 128KBPS Venice Classical Radio.eu from Italy, and heard reasonable depth and dimensionality from a recording of Brahms Piano Sonata No. 2, as well as an excellent feeling of weight and power from the piano’s lower registers. Switching to Boston’s WGBH at 160kbps feed on the TuneMark radio app I was greeted by a series of sonically spacious recordings that brought back fond memories of my time living in Boston and regularly attending the Thursday evening concert series.

 

Because I could, I also compared the sound quality of the WGBH 160kbps Internet radio feed of the Hyperion Trio playing Mendelsohn’s Piano Trio Op. 49 routed from the iPhone 5 into the PHA-2 and then out to an analog input on a Wyred4Sound mPre with that same Internet radio feed also coming through my MacPro’s iTunes into the Wyred4Sound mPre DAC via its USB 2.0 connection. After matching the output levels, I found it was virtually impossible to tell a difference between the two radio feeds. Both were equally spacious, dynamic, full-range, and detailed. When the program material changed to the BSO conducted by James Levine playing Mozart’s Symphony No. 14, I was immediately aware on both sources of the slightly astringent sound of the string section and the overly reverberant recording technique.

Conclusion
Some prospective owners may find my main ergonomic issues with the PHA-2 are its greatest strength—its solidity and weight. The PHA-2 isn’t even close to being in the running as the most “travel-friendly” portable DAC/headphone amplifier I’ve used, weight-wise. Compared to the Resonessence Herus or AudioEngine A3, the PHA-2 is massive. When I recently attended AXPONA in Chicago I opted to carry the Astell&Kern AK100 as my primary portable audio device because of its much lighter weight and far smaller footprint. If faced with equal levels of travel-induced trauma, the PHA-2 would undoubtedly survive better than the AK100, but at the cost of its additional weight and bulk.

As consumers demand more “one-box” solutions for computer and portable-audio playback, we’re beginning to see a steady stream of new DAC/headphone-amplifier products designed for both home and travel use. The Sony PHA-2 offers a lot of capabilities and excellent sound for under $600. But since no one device can do everything, prospective owners should look at the PHA-2’s feature set carefully to ensure that it does what you need it to do. If you plan to use it with especially difficult-to-drive headphones, you should definitely audition it with those headphones before making a final purchasing decision. While the PHA-2 does drive higher-impedance headphones such as the 600-ohm version of the Beyer Dynamic DT-990 with more authority than the Astell & Kern AK100, most users are unlikely to carry this type of headphone while traveling. For those audiophiles who strongly favor a difficult-to-drive headphone, the PHA-2 will be a better option than the headphone amplifiers built into most portable devices. Also for owners of highly sensitive, custom, in-ear monitors, who are tired of listening to the low-level background hiss that emanates from many headphone amplifiers, the PHA-2’s lack of noise and hiss could make it an ideal pairing for the Westone ES5 as well as many other custom high-sensitivity in-ears.

SPECS & PRICING

Digital inputs: USB Micro-B input (for charging & PC), USB Mini-B input (for Walkman), USB Standard type A (for iPod/iPhone/iPad)
Recharging time: Approx. 7 hours
Outputs: Phones (stereo minijack, only 3-pole supported), Audio In/Line Out (stereo minijack, only 3-pole supported)
Analog input: One
Output power: Approx. 165mW+165mW (8-ohm, 10% distortion); approx. 90mW+90mW (32-ohm, 1% distortion); approx. 25mW+25mW (300-ohm, 10% distortion)
Input voltage: Maximum: 1V RMS
Dimensions: 2.67″ x 1.14″ x 5.5″
Price: $595

Read Next From Review

See all

Adblocker Detected

"Neque porro quisquam est qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit..."

"There is no one who loves pain itself, who seeks after it and wants to have it, simply because it is pain..."