Hey ASR,
LONG TIME lurker here. I recently purchased a SMSL SU-9 to go along with my THX 889 > Driving Senn 800s/Arya/Ananda/M4U1/Q701/MDRV6
I get occasional static coming from my SMSL SU-9. Just to verify, I have tried the setup on another PC/optical connection to a TV/Bluetooth to a phone...