Sony PHA-2

Portable headphone amplifier/USB DAC

Item #: 158PHA2

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High-res audio

A portable high-res powerhouse

Smartphones and portable music players are pretty amazing devices, but sometimes the sound quality of their headphone outputs can leave you flat. That's because cost constraints and power consumption issues usually rule out the use of high-performance headphone circuitry. That's where the Sony PHA-2 headphone amplifier and digital-to-analog converter comes in.

Small enough to take almost anywhere, it connects between your music player's or computer's headphone jack or digital output and your headphones to deliver the serious punch and clarity your tunes deserve. And for high-res music lovers, the PHA-2 can even decode PCM digital audio signals up to 24-bit/192kHz resolution and DSD audio sources at 2.8MHz / 5.6MHz, so you can enjoy better-than-CD audio quality. This potent little headphone amplifier's rechargeable battery supplies the power you need to pump out bigger, bolder sound. You'll immediately experience greater bass extension and low-frequency impact, along with more dynamic, detailed sound.

Versatile connectivity and sturdy construction

Sony PHA-2 headphone amp/DAC

Sony's rugged PHA-2 features strong alloy bumpers to protect the volume knob and headphone connector.

The PHA-2 works with a wide array of devices. Its three separate USB ports give you a direct digital connection for your iPod®/iPhone®/iPad®, hi-res Walkman®, and a PC or Mac®. This allows the Sony to bypass the DAC in your player or computer, and decode your tunes with superior audiophile-quality precision. The PHA-2 also offers an analog input for connecting most MP3 players, smartphones and other audio devices, as well as a line output for connecting to a receiver or self-powered speakers.

Built like a Swiss watch, this Sony's rugged aluminum enclosure protects the presicion circuitry inside from outside interference and impacts. Strong alloy bumpers also help protect the volume knob and headphone connector. Plus, recessed control switches reduce the chance of accidental access during playback.

Looking for great-sounding headphones for this headphone amp/DAC? Check out our selection.

From our Sony PHA-2 portable headphone amp/DAC review:

I began my high-res listening with “Life in the Fast Lane” by the Eagles, a song I must have heard hundreds of times. Yet listening to it with the PHA-2 was like hearing it with fresh ears. The layering of guitars in this song is masterful, and I found myself marveling at Joe Walsh's well-placed fills. I even noticed some guitar amplifier hum in the song's intro – something I'd never picked up before.

— David Brown, Crutchfield A/V Writer

Product Highlights:

  • battery-powered portable headphone amplifier with built-in USB DAC
  • decodes PCM digital audio sources up to 24-bit/192kHz
  • decodes Direct Stream Digital (DSD) files at 2.8MHz or 5.6MHz resolution
  • asynchronous USB data transfer for reduced timing jitter and better sound
  • TI PCM1795 32-bit/192kHz DAC for precise playback of digital music files
  • analog volume knob provides fine level adjustments without degrading audio quality
  • gain select switch provides compatibility for a wide range of headphones and earphones
  • three USB ports:
    • micro type-B input for charging & computer connection (adapter cable included)
    • mini type-B input for Sony Walkman™ (adapter cable included)
    • standard type-A input for iPod®/iPhone®/iPad® devices (these devices must use their own respective cables, not included)
  • combination minijack audio input/line-level output for connecting MP3 players, smartphones and other audio devices or driving an external amp or powered speakers
  • built-in lithium-ion rechargeable battery provides up to 6.5 hours of playback with USB digital source (up to 17 hours when connected to analog stereo input)
  • durable aluminum body with alloy bumpers to protect volume control and headphone jack
  • recommended headphone impedance: 8-600 ohms
  • distortion: less than 0.01% (1kHz)
  • frequency range: 10-100,000 Hz (analog audio input)
  • 2-3/4"W x 5-5/8"H x 1-3/16"D
  • weight: 9.52 oz.
  • warranty: 1 year parts, 90 days labor
  • Our 60-day money-back guarantee

Why buy a headphone amp?

High-performance headphones need high-quality amplification to perform up to their full potential. If you connect them directly to the headphone jack on your computer, iPod®, or stereo receiver, you may be disappointed. A separate headphone amplifier sends a stronger, cleaner signal to your headphones.

Hands-on research

What's in the box?

Download owner's manual

  • Headphone amplifier
  • 59" Micro USB cable (Type A USB on one end and Micro USB on other end)
  • 4 Silicone belts
  • Protection sheet
  • 4.25" Miniplug cable (right angled 3.5mm male miniplug on each end)
  • 4.5" Walkman cable (for special high-resolution supported Walkman)
  • Operating Instructions (3 versions - Eng/Fren/Span)
  • Listening for a Lifetime (brochure on headphone safety) from Sony
  • Listening for a Lifetime (brochure on headphone safety) from CEA
  • Warranty sheet (USA)
  • Warranty sheet (Canada)

Product Research


Overview: The Sony PHA-2 is a battery-powered portable DAC (digital-to-analog converter) and headphone amplifier that lets you listen to high-resolution audio through your headphones. You can connect a PC, an iPod/iPhone/iPad, or a high-res capable Walkman to the unit using one of the three USB inputs. It will also work with analog devices as well.

Internal Components and Construction: The PHA-2's PCM1795 DAC samples PCM audio at 192kHz/24-bit, and DSD audio at 2.8/5.6MHz. The LME49860 operational amp delivers outstanding audio performance with virtually no distortion or noise. The TPA6120 headphone amp provides a wide 120dB dynamic range to make sure you can hear every detail in the music. On the outside, the unit features a compact brushed aluminum enclosure to protect the inside circuitry and components. Aluminum alloy "bumpers" on the ends provide further protection of the connecting cables and volume knob from hard impacts.

USB 2.0 Clock: The DAC is equipped with an asynchronous USB 2.0 clock signal generator that reduces timing inaccuracies when converting digital signals into analog waveforms. This results in a highly accurate DA conversion and jitter-free audio for superior audio reproduction that is as close to the original recording as possible.

Digital/Analog Connections: The PHA-2 has three USB digital inputs: a Micro USB port for PC and charging, a Type A USB for connecting an iPod/iPad/iPhone, and a Mini-B USB with an extra pin for connecting a High-Res supported Sony Walkman. The front panel features two stereo 3.5mm jacks--a headphone output and a Line Out, which doubles as an analog stereo input.

Note: The 3.5mm inputs only support 3-pole stereo miniplugs. Other plugs, including 2-pole and 4-pole stereo miniplugs are not supported.

Controls: The front-mounted large power/volume control knob with plenty of headroom to let you set the volume just where you want it. A 2-position gain switch (normal/high) on the side lets you match the headphone amp to various headphone impedances from 8 to 600 Ohms. Another 2-way switch is provided for selecting the output--headphones or the line output. On the back, there's a 4-way slide switch for selecting between the three USB inputs and the analog input.

Lithium-ion Rechargeable Battery: The PHA-2 is powered by a built-in 3.7-volt Lithium-ion rechargeable battery. The battery charges in approximately 7 hours via USB when connected to a PC. With the optional AC-UD20 USB AC adapter, charging time is only 3.5 hours. Battery life is approximately 17 hours with an analog input connection and 6.5 hours with a digital input connection.

Compatible Devices: The Sony PHA-2 is compatible with a wide variety of devices. With three USB inputs and an analog input, it can connect to most computers and portable audio devices:

  • Computer: The unit can play digital audio files stored on your computer. The unit includes a Micro USB cable for connecting it to your computer's USB Type A port. The PHA-2 is compatible with the following Operating Systems: Windows 8, Windows 7 (SP1), Windows Vista (SP2), and Mac OS X 10.6.8 or later. Note: For Windows PCs, you must first install the driver software "Sony Portable Headphone Amplifier USB Audio 2.0 Driver" before connecting the PHA-2. Playing high-resolution audio files on your computer may require you to download and install "Hi-Res Audio Player" software to your computer.
  • Apple Devices: The PHA-2 is compatible with iPhone, iPad, and iPod. The Type A USB input is provided for connecting the i-device using the USB cable provided with the device. The digital audio data from the device is transferred directly to the DAC, and bypasses the device's internal DAC. Compatible models include:
    • iPhone: 5S, 5C, 5, 4S, 4, 3GS
    • iPad: 4th gen, 3rd gen, mini, iPad 2, iPad
    • iPod:
      • touch: 5th gen, 4th gen, 3rd gen, 2nd gen
      • classic: 120GB, 160GB
      • nano: 7th gen, 6th gen, 5th gen, 4th gen, 3rd gen
  • Sony Walkman: The PHA-2 is compatible with high-resolution supported Sony Walkman devices, such as the NWZ-F880 series. The portable DAC/headphone amp comes with a USB cable that has a connector that plugs into the Walkman's proprietary output port. The DAC has a dedicated USB port with an extra pin that accommodates the Walkman cable. Like the Apple devices, the digital audio data bypasses the Walkman's internal DAC and is sent directly to the PHA-2's digital-to-audio converter.
  • Other Devices: The PHA-2 lets you listen to music on other audio devices, such as a smartphone or portable music player, through the analog audio input.

Silicone Belts: The PHA-2 is designed to allow you to conveniently attach your portable device to the top. Two rubber rails, approximately 1-3/4" apart, let you rest your player on the top and secure it with two of the provided silicone belts. The belts lock in place in two grooves that run along the sides of the portable DAC. If your player is not wide enough to rest on the rails, a silicone rubber protection mat is provided to prevent scratches.


  • Frequency Range: 10 Hz - 100 kHz (Audio In input)
  • Distortion: 0.01% or less (1 kHz)
  • Supported Impedance: 8Ω - 600Ω
  • Maximum Input: 1 Vrms (Audio in)
  • Maximum Output (with built-in battery):
    • 165 mW + 165 mW (8Ω, 10% distortion)
    • 90 mW + 90 mW (32Ω, 1% distortion)
    • 25 mW + 25 mW (300Ω, 10% distortion)

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.

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