Can XLR to RCA affect input impedance of amp?

My Proceed HPA-2 amp has an unbalanced input impedance of 11 ohms and a balanced input impedance of 100. Theoretically the higher input impedance would work better with my preamp (Hovland) which has a high output impedance. Problem is that although the Proceed has balanced inputs, the Hovalnd does not have balanced outputs. So I have two questions. First, would running an interconnect with XLR at the amp end and RCA at the preamp end (assuming that is even possible) increase the Proceed's input impednace? And, second, is there some sort of an adapter to change one end of an RCA interconnect to XLR?