Noob here, so I apologize in advance for not really knowing what I'm doing.
Backstory: I've been running the Crack 1.1 with Speedball upgrade happily for around three months into HD600s (it really does sound fantastic). My setup has been optical out of my computer into a Geshelli Labs Enog Pro Dac split into a JVC SP-UX7000 receiver and the Crack.
Problem: Fast forward three months with no problems and I decide I should hook my Blu-ray player up to the DAC as well. As soon as I plug it into the DAC via coax, a noticable buzz starts in both channels on the crack, but I do not hear it through my speakers. The buzz changes when I move the mouse on my computer or run programs, so I unplugged the optical from my computer (about 5 feet away from the Crack), but the buzzing and mouse movement changes persisted. I shut my computer down and the buzzing still didn't go away. It stopped when I unplugged the coaxial cable.
Swapping cables didn't help. Unplugging the receiver didn't help. Re-heating the solder joints around the power and rca jacks didn't help. I was able to run a DIY O2 Amplifier without hum from the DAC with both coax and optical plugged in, and was able to run the Crack off a different DAC I borrowed from a friend using both coaxial and optical without any buzzing. I also tried a different device with coaxial out instead of the blu-ray player and had the same buzz. All the devices are running off the same surge strip.
I'm not sure what else to try or why this is happening.
Any suggestions?