Strange ground loop...?

I just hooked up a new amp and I'm having a strange noise issue. Only in my right channel, I get this high-pitched whine... maybe around 2khz. My left channel is dead silent.

The problem seems to be an interaction between my DAC and my amp. If the DAC is off, the amp is silent.

At some point in your trial and error testing did switch, cross, the ics at the amp? (Switch the right with the left at the Amp, one end only of the ics.) See if the buzz then goes to the other channel of the amp. This will kill two birds with one stone, so to speak, the Dac as well as the ics.

The amp is an 84' yamaha, so the cord has no ground. There is a ground screw, though, and I have connected that to my power conditioner, hoping this would solve it... nope.

The amp, I assume, has a built-in phono preamp. The ground screw is for the ground wire of a TT, not to connect the amp to earth ground.

Is the plug on the cord of the amp polarized? One blade wider than the other? Can you plug the plug into the wall receptacle in either direction?

I suspect I just need to find a proper place to run that ground wire...

I would not recommend connecting the chassis of the amp to earth ground.... It can cause more harm than good.

Hmm, no phono in... just a pair of RCA's. It's a Yamaha M-40 power amp.

The plug isn't polarized.

In the manual, it says to connect the ground to the pre-amp ground if there is a buzz. Unfortunately my pre-amp has no ground.

You were right about switching the ICs. Last night I started to think... 'wait, this doesn't make sense that it would only be coming though one channel.' I swapped the ICs with another pair, and the issue was solved.

I have no idea how this could happen - maybe something is wrong with the shielding on one of my ICs? They are brand new, so I didn't suspect that at all.

Incidentally, I had to turn my amp on and off many times while switching power configurations around. Also, some music was distorted in that right channel (crackly, fuzzy) at times... could any of this have damaged my amp / speakers?

IC shield is grounded at one end only (if it's RCA). Try to reverse one that gives you trouble.