iFi Audio Zen Can 3

Bass Boost, gain switch

iFi Audio ZEN CAN Signature

Bass Boost, gain switch

Hifiman EF500

gain switch

FiiO KA2

USB-DAC

FiiO KA11

USB-DAC

FiiO BTR15

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

FiiO LT-TC5

Lehmann Audio Drachenfels

RME Audio RME ADI-2/4 Pro SE AD/DA converter with microfibre cloth

Mackie Hm-800

gain switch

FiiO K11 R2R

Display, gain switch, USB-DAC

Terratec HA-1 batch

Bass Boost, Powerbank

InLine Replacement Tube for AmpUSB HiFi DSD Headphone Tube Amplifier

Mackie Hm-400

PreSonus Headphone amplifier HP60