Used Headphone amplifiers

FiiO K7

USB-DAC, gain switch

FiiO KA5

USB-DAC

FiiO KA1

USB-DAC

FiiO KA2

USB-DAC

FiiO K11

Display, gain switch, USB-DAC

iFi Audio GO link

USB-DAC

FiiO BTR3K

Bluetooth

FiiO K7 BT

USB-DAC, gain switch, Bluetooth

RME Audio ADI-2 DAC FS

Display

iFi Audio ZEN DAC V2

gain switch, Bass Boost, USB-DAC

TIE Headphone Amplifier 4CH

Lake People MC100

iFi Audio xDSD Gryphon

Display, Bass Boost, USB-DAC, Bluetooth

Chord Hugo2

USB host, USB-DAC, Bluetooth

Mackie HM-4