Amazon.com: EPOS I Sennheiser GSX 300, Gaming Dac/External Sound Card with 7:1 Surround, High Resolution Audio EQ presets for Gaming, Movies and Music - Audio Gaming Amplifier for PC and MAC Compatible,
EPOS|Sennheiser GSX 300 External USB Sound Card (updated for confusing corporate reasons) - GadgetGuy
Mini sound card under test: EPOS│SENNHEISER GSX 300
EPOS introduces GSX 300
EPOS GSX 300 External Sound Card Review - PC Perspective
GSX 300 from EPOS | One small device for a huge step-up in audio