[PROBLEM] NuForce DAC100 Glitches above 16/44.1.

[leicray]

I think that you might be experiencing the "popping" problem about which there is a lengthy thread:

http://moodeaudio.org/forum/showthread.php?tid=205

The basis seems to be a USB mismatch between between the Pi4 and the DAC. I experienced something similar with an Audiolab M-DAC when using a Pi4, though it works fine using a Pi2B+.