My A65 has started a low background buzz through one speaker regardless of source etc etc. From powering up it starts as the audible 'clunk' does (really hope you know what I mean by that!) It also seems more sensitive to movement than before -i nudged it while checking connections and it switched off and clunked in again (the power and input selector lights stayed lit). This is a second hand amp that has worked well for me for over a year. I'm new to this so go easy if I'm being a muppet!