I just switched my feed over to a thin client server and have a hum now. Anyone in the Sacramento area have a USB sound card they would want to let me try? If you have a spare and it fixes it I will buy it.
The hum is typically caused when you use the headphone output of a GRE scanner. There is no ground on that connector so you get a hum. If using a GRE scanner, use the ground from the antenna connector (or external power) for the audio ground and the hum will go away.
Got it taken care of now. I was using a barrel plug splitter, on side to power the thin client with the other going to power the mobile scanner. Once I used a seperate power supply the hum was gone. At first I thought it was just a crappy onboard sound causing it.
It is a Radio Shack mobile scanner and a WYSE thin client.