Next steps are:
1) build John Swenson's 5V power supply to supply my DAC. I'm making a dual headed USB A -> single USB B cable for this purpose.
2) upgrade power cable and power strip.
3) I was considering running the +/- lines of one of the balanced outputs (either R or L) into the Crack (R/L RCA in) just to see if that eliminated the hum but I'm on the fence as to whether that would be worth it.