My wife is on a trip to San Diego. She called me saying the rear speakers are shot. I've yet to look at it myself, so that's neither here or there. She has complained for months about a bad Aux cable, which she was never able to duplicate and which went away on its own. But if the speakers did go bad, what are the options to replace them? Does having the HK system add complexity to this?
"add complexity" ... oh yes! Assuming R50/R52/R53 not R56. The H/K system amp and speakers are an integrated whole. The rear speakers for example are dual voice coil, each coil two ohm impedance. So four amp channels drive the two rear speakers. You can find ripped out H/K speakers - but I'd be much more likely to suspect that the H/K amp is going bad and making the rear speakers sound bad, rather than the speakers themselves are bad.