Use amp in balanced mode in unbalanced set-up

Your best bet would be to call Ayre next week. This is not something a casual reader here could respond to without guessing. Even seeing your system first hand, the answer might not be obvious, because this is the kind of thing that should be addressed by someone familiar with the circuit design of your components.

OK, you want me to guess? Lift the ground pin on the amp power cord (keep preamp grounded) return mode to unbalanced, and test. Should be OK. If not, go no further. Call Ayre.

The very idea of ballanced is to "Farris Buler...Buler...Buler" yes - cancel noise! and though there usually mabe could be negatives, sometimes you can get lucky and everything matches up and no percieved negatives. Forget the science and trust your ears.