Used Headphone amplifiers

FiiO KA11

USB-DAC

FiiO K11 R2R

USB-DAC, Display, gain switch

IK Multimedia Arc On-Ear

USB-DAC

FiiO K11

USB-DAC, Display, gain switch

FiiO K7

USB-DAC, gain switch

iFi Audio Zen Dac 3

Bass Boost, USB-DAC

Hifiman EF600 Headphone Amplifier

USB-DAC, Bluetooth

FiiO K13 R2R

USB-DAC, Display, Tone control, gain switch, Bluetooth

Fosi Audio K7

Display, Bluetooth

iFi Audio Go link Max

USB-DAC

FiiO QX13

USB-DAC

FiiO BTR17

Microphones, USB-DAC, Tone control, Display, Bluetooth

Hifiman Serenade

USB-DAC, Bluetooth

iFi Audio GO link

USB-DAC

Mackie Hm-4