Hey guys, I am banging my head around a possible ground loop.
My stereo system comprises of: DS senior DAC - Pass Labs XP30 preamp - BHK300. All of them fed by a P10.
To multichannel, I am using a Yamaha RX-a3060 receiver. The power section of the receiver goes to center and surround channel, and the preamp section of the receiver goes into de Pass Labs preamp.
The problem is that I get a 120hz buzz when I select the input to which the receiver is connected. The buzz varies with the volume, all indicating a ground loop. I have no issues with the DS DAC. Dead quiet, using either XLR or RCA. Tried changing cables, moving the receiver around etc.
The problem I think lies in that the receiver is class 2 device (double insulated), using a 2-prong AC cord, and no ground connector at the chassis. The only ground connector is for the phono input. Should I connect a grounding wire to this phono input? Or should I open the receiver case, and look for the star grounding point (if there is any)? Or is there any other approach I can use?
By the way, I can replicate the problem with others 2 prong AV receivers borrowed from close friends.