I'm considering upgrading the power amps for my side and rear speakers but don't know how much I should be looking to spend for a worthwhile improvement. I'm currently using a pair of Arcam 290p's (same as Alpha 9p) with a Lexicon MC1 processor and Monitor Audio silver fxi speakers. I've bi-amped the fronts with Arcam P25/P35 but don't really want to spend that sort of cash on rear power amps. A single box solution would be nice. Would a Rotel 1075 be an improvement or more of a side step? Any advice would be appreciated.