[mrip541]

I have 3 sets of ICs. When used between my dac and my amp, there's a strong buzz with 2 of them. With one of those two the buzz will change based on touching the metal of the connectors or simply moving the cable around. With both of them the buzz goes away if I unplug the usb connection between the dac and pc. With the 3rd set it's always dead silent. What could be wrong with the 2 that buzz?

 

[yage]

Sounds like a ground loop issue. It could be the two IC's that produce buzz have their shield (if present) improperly connected - i.e. both ends of the shield connected to ground. Another possibility is that the connection between the wire and the plug are loose. Does your DAC share the same power outlet as the PC?