Amazon.com: Gomadic Portable AA Battery Pack Designed for The Sony PHA-3 USB DAC Headphone Amplifier - Powered by 4 X AA Batteries to Provide Emergency Charge. Built Using TipExchange Technology : Electronics
Zishan U1 IP5332 power supply with 4200mAh battery USB dac decoder sound card compatible Amanero XMOS F10 009|Amplifier| - AliExpress
XDUOO XD05 PLUS Battery-Powered Portable Headphone Amplifier AK4493EQ XMOS 32bit 384kHz DSD256 Black - Audiophonics