The Sony PHA-1 Portable Headphone Amplifier and USB DAC can be used for portable audio playback from analog and digital audio sources such as compatible computers or iOS devices. It has a built-in digital to analog converter with asynchronous digital transfer to reduce jitter. It supports sampling frequencies up to 24-bit/96kHz. The PHA-1 has a micro-USB input for use with compatible computers as well as a dedicated digital input for iOS devices. It also supports analog audio sources via its 1/8" stereo mini jack input.
The amplifier comes with a built-in rechargeable battery that provides up to 10-hours of playback when in use with an analog audio source and up to 5-hours of playback with a digital source. Its gain switch provides compatibility with a range of headphones ranging from 8 to 600 ohms. The unit's analog and digital circuits are isolated and housed in an aluminum-shielded case to reduce electrical noise.