Damage? Not likely. Well, excess humidity, and heat can damage something but not in a subtle way. Usually this evidences by loss of functions, cracking or popping sounds or total loss of bass or treble, scratchy volume controls, etc.
Otherwise, the room, power and Class D amps may be the culprits. Nothing wrong with Class D, but some take 3-4 days to warm up after being powered off for any length of time.
In your case I suspect the issue is more ot do with rotating the system around without significant room treatment on the side walls.