I sold my McCormack DNA-500 to a guy with an agreement that he could audition it and decide whether to go through with it. He uses his Bel Canto Dac3 as source and preamp. He goes directly into the amp, and I have asked whether he uses balanced XLR cables or s/e RCA cables but I have not heard back yet.
The amp sounds great with his Wilson Benesch speakers, but the problem is a buzz/hiss that is present and presumably most noticeable in quiet passages or when there is no music playing. He has contacted SMc Audio, Steve McCormack's shop, and has done what they have suggested (cheater plug, switch outlets, try a line conditioner and direct into outlet, etc) to no avail.
I am not sure if it is some kind of ground loop or impedance mis-match or what. If he is using RCAs, could XLRs possibly solve any issues? I have some Jensen Iso-Max transformers like these:
I could see if one of those worked for him as well as they worked for me when I had a similar thing going on. Any smart and knowledgeable Head-Casers have any suggestions for how to explain or resolve this mess? Thanks in advance.