Amazon.com: FiiO K3 Type-C USB DAC Headphone Amp : Electronics
Gomadic High Capacity Rechargeable External Battery Pack suitable for the Sony PHA-3 USB DAC Headphone Amplifier
Lt3042 Low Noise High Precision Linear Regulator Power Supply 5v 1.5a Dc Power Battery Powered Usb For Hifi Audio Dac Decoder - Home Theater Amplifiers - AliExpress
iFi Audio xDSD Portable USB DAC and headphone amplifier with Bluetooth® at Crutchfield