The HA-2 from Chinese manufacturer Oppo, is a portable headphone amp, DAC and mobile charging device.
It is designed to work with iOS, Android and Windows mobile devices, plus PC and Mac desktop machines.
In the box you will find a variety of connecting cables and two rubber bands to strap your phone to, and the unit is wrapped in leather so you won't have to worry about it scratching your mobile device.
The HA-2 supports PCM audio up to 384kHz/32-bit and DSD audio up to 12MHz (DSD256 or DSD4x). You will, however, need a high-res audio playback app on your device of choice. But even if you don't, there is a big difference in sound quality even when listening to standard FLAC or 320kbps MP3 files.
Don't feel you need to pair the HA-2 necessarily with the PM-3 (although the results are stunning); it will improve the listening experience with any in-ear, on-ear or over-ear headphone regardless of impedance.
There is enough power in this unit to sate the most hungry of power-sucking cans. If you find it lacking on the volume front then there is a high and low gain switch with volume fade in/out function to protect your hearing.
We would suggest keeping it on the low setting for most headphones though, as the high setting is loud and capable of delivering up to 300mW into 16 Ohm headphones. And if you want to spice up a flat signal with extra low-end, there's also a bass-enhancement function which is produced purely via the analogue circuitry – not that you will ever really need it.