I have a Sony STR-DE545 that recently started acting up. The 'A' speaker channel shuts itself off and if you tap the receiver, it will usually come back on. I've had a very hard time finding any place that is willing to repair this, or charge me a reasonable price for the repair. I know I don't know everything about home audio equipment, but it seems to me that this shouldn't cost more than $100. The receiver only cost $259.