For measuring my system, I was struggling with not having a floating USB sound card to use with Pete Millett’s interface. I found a cheap alternative (Focusrite Scarlett 2i2) which can do ASIO 96kHZ and 24-bit.
Above is the response with internal loopback at 1Vrms on the 2Vrms scale of the SC interface.The distortion is really good below 0.01% just above 25Hz:
With the balanced input and outputs the noise level is really low. Below -120dB mostly across the entire 20Hz – 50kHz band. Inband noise level is below 100uV when the DAC volume is at highest level and the ASIO generator is muted:
For distortion testing this USB audio interface has a very good oscillator output performance. Check out the 100mV level below:
