Have you ruled out an issue with your left speaker connection? Literally the terminals and wire at the speaker?
10 responses Add your response
Yes, and, no. By swapping out the integrateds, you've eliminated that variable. Trying different speaker cables will determine whether your next step would be the speakers. Something could have slipped past QC at the factory, only to assert itself in your system.
Step by step is the only way to go.
All the best,
Wiring could have a very small short that only shows itself when there is enough current-potential to over come the resistance in the short, that could show up as an intermittent problem. If your wiring is in your wall then only way to check that is a megger. Most electricians will have one in their multi-meters. get another set of wires and try that, don't have to be fancy any lamp cord will work for fault finding purposes. switch speakers too to eliminate them as a culprit.