Saturday, May 23, 2015

Sony MDR-Z7 Headphones and PHA-3 Portable Headphone Amplifier

Sony PHA-3 Portable Headphone Amplifier


The Sony PHA-3 is a compact battery powered DAC / headphone amplifier. Size-wise, it is the perfect partner for the NW ZX-2 walkman and provides the additional drive required for more difficult headphone loads. 


The palm sized PHA-3 is aluminum finished, with the volume knob and headphone jacks on one end, with inputs, line output and the power jack on the other side.

The front panel has 3 LEDs that indicate high frequency sampling rate (anything above 48 kHz), DSD operation and power / charge status.

Two rubberised strips on both the top and bottom of the unit provide the unit with a bit of extra grip to prevent the unit from sliding on flat surfaces.

Measuring  80 x 29 x 140.5 mm (WxHxD), the PHA-3 weighs a very healthy 300 g.

The PHA-3 is well specified with playback of file resolutions of up to 32 bit / 384 kHz sampling rate supported via USB connection, or 24 bit / 192 kHz via the Toslink optical jack. DSD is supported at both 2.8 MHz and 5.6 MHz.

USB input is via either a micro USB port or a type A socket.

A line input is also provided to allow the PHA-3 to act as a headphone amplifier with analog signals.

The headphone amplifier is robustly specified at 100 mw per channel (32 ohm loads at 1% distortion) for normal operation, and 320 mw per channel for balanced operation. 

The PHA-3 has a built-in lithium-ion battery which is charged via a micro USB jack. Battery life is specfied at 5 hours if balanced operation and the DAC is used. Using the PHA-3 as a headphone amplifier only (i.e. via the analog input) lengthens the battery life to 28 hours.

One headphone jack (3.5mm) is provided, with a second pair of jacks (3.5mm also) for balanced operation. 

Two side mounted switches control gain and DSEE HX (Digital Sound Enhancement Engine) which upscales lossy music files.


The PHA-3 is generally easy to operate. The unit is switched on via the volume knob and the power / charge indicator will flash briefly to inform the user of the battery level (3 flashes indicating full charge). 

The unit charges fully in about 10 hours if charged via a computer USB port. An optional AC adapter shortens charge time to 6 hours.

By the way, Sony is not joking about the battery life. I obtained an average of about 4 hours of use from the PHA-3 using both the DAC and balanced operation. Better bring along a battery charge bank for longer journeys !

If you are using the PHA-3 for desktop use, it can be powered continuously. Sony's manual states that the PHA-3's battery is not charged unless the unit is switched off. My personal experience suggests otherwise. I discharged the battery until it was nearly empty and then hooked it up to a computer USB port. I managed to get about 50 % charge after about 10 hours. It definitely charges when switched on, albeit slowly.

Connecting the PHA-3 to various computers around the house and both iOS and Android mobile devices for PCM playback was fuss-free. For DSD playback, I could only get the PHA-3 to work reliably via the Sony provided software player. Fiddling with Foobar got me nowhere, while I managed to get a few seconds of playback via Pure Music, followed by loud bursts of static. I did not have a compatible Sony Walkman, so I am not sure whether the PHA-3 can play back DSD files directly from such devices.

In terms of drive ability, the PHA-3 had no problems with either a Beyer DT-880 (250 ohm version) or Sony MDR-Z7 (for both normal or balanced operation) to ear splitting volumes. 


The PHA-3 sounded great as a DAC / headamp.  Bass was authoritative and full, while high frequencies were extended and clean. Midrange tone was slightly laidback and sweet though. Resolving quality was quite good and the low level details in my usual test tracks were reproduced without any issue.

Pairing with the Beyer DT-880 proved to be a great match. The DT-880 can sound overly bright and lean with the wrong source and amplifier match. The midrange sweetness and full bass of the PHA-3 proved to be a nice counterfoil to the DT-880's fast and analytical character. 

The PHA-3 performance in balanced operation was exemplary. The MDR-Z7 was the only headphone I had on hand with appropriate wiring for the PHA-3. In this case, the Z7 gained additional authority and clarity in bass lines. There was also an improvement in speed and separation, especially during busy mixes. I would even dare to suggest that the PHA-3 and Z7 were truly made for each other.


The PHA-3 is an interesting animal. It has a great DAC and headphone stage, but battery life is frankly underwhelming. What really sold me on the PHA-3 was balanced operation.

The review sample was kindly supplied by Sony Singapore through it's media partner, Waggener Edstrom.

Recommended Consumer Price - SGD 1,199

Sony MDR-Z7


Readers may wish to refer to my earlier article that featured the MDR-Z7, as it provides some insights into its design (click here for the earlier article). 

The kind folks at Sony had offered the Z7 together with the PHA-3 for purposes of this review, but I had already purchased the Z7 sometime back, so a review sample was not necessary.


The Z7 is Sony's newest flagship headphone. Sporting massive 70 mm Aluminum-coated Liquid Crystal Polymer diaphragms, the Z7 has a rated frequency response from 4 Hz to 100 kHz.  

Sensitivity is rated at 102 db/mW, with an impedance of 70 ohms (at 1 kHz). These specifications suggest that the Z7 is quite easy to drive, which was borne out by listening tests.

With a weight of 335 g, the Z7 is of moderate weight, but the physical size of these cans means that the Z7 is happier at home than on the go.

Sony thoughtfully provides a 3 m silver-coated OFC cable, as well as a shorter 2 m balanced cable. Cabling attaches to the Z7 via twin locking 3.5 mm plugs.The balanced cable is terminated on the source end via twin 3.5 mm plugs too. In case you are wondering why Sony did not terminate the balanced cable in a more common way, like twin 3 pin XLR plugs, or a single 4 pin XLR plug, the answer is obvious once you look at the pictures of the PHA-3 above.

Despite the locking sleeve, any ordinary 3.5 mm plug will fit nicely into the jacks on the headphone end. 

The Z7 is a closed design. Twin vents (on the top and bottom of each earcup) result in some leakage of sound, albeit only a high volumes. 

In Use

Comfort and fit is first-rate. The soft leather-feel earpads are some of the most comfortable pads I have used. They do heat up very fast in tropical weather, and periodic rest is required even in air-conditioned environments.

The adjustable headband has numbered graduations internally, making it a cinch to revert back to your preferred adjustments quickly. The headband fit my smallish head well, without exerting too much pressure on either my ears, nor the legs of my eyeglasses.


I paired the Z7 with a variety of headamps and sources I had on hand, before settling for the PHA-3 and a Violectric V281 (used as both a headamp and DAC). As I did not have the right cable, I could only use the normal outputs on the V281 rather than the balanced drive outputs.

The first thing that grabs your attention is the bass. The Z7 has powerful and thumpy bass lines. The problem is that the bass frequencies overwhelm the rest of the frequency spectrum and have a slight lack of control.

The midrange has a slightly laidback and sweet presentation. High frequencies are extended but well-behaved. Subjectively, the high frequencies seem to have less prominence compared to some of my other headphones. Initially I thought the Z7 sounded a bit dark and rolled-off, but this depended on the bass content of the track in question. The Z7 sounded wonderfully open and detailed on violin solos and very much less so on pop and rock tracks.

Staging wise, the Z7 is above average with a spacious soundstage (no doubt with some assistance from the angled drivers), and very good detail retrieval. 

Moving on to balanced drive, this is where the Z7 shines. With the PHA-3, the issues I had with the bass were largely addressed, with the low frequencies gaining tightness, control and explosive dynamics. Similarly, an increase in speed and incision lifted the midrange and treble to a faster and closer to neutral presentation. 

Notwithstanding the above, the Z7 (especially as a flagship model) is not a neutral headphone. My ownership experience so far parallels that of the Audio Technica ATH-W5000. Some tracks will leave you incredibly frustrated, while selected tracks will leave you in sonic bliss. Thankfully, balanced drive made the ownership experience more pleasurable than otherwise.


The Z7 is an idiosyncratic headphone - a detailed listen should make it clear whether you like it or not. However, in order to fully exploit it's capabilities, balanced drive is mandatory.

Recommended Consumer Price - SGD 899  

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