i brought out the whole speaker ensemble (5 speakers) to the balcony this weekend & found that the main speaker isn't going on. typically it runs in the room but i've left it unplugged sitting for a month for no particular reason. i need to try another amp, but pretty sure it's the amp. i'm sad about it but also served me very well for ~3 years, is cheap, and i love the dude doing these so much.

$60 + $10 tax & shipping for a new 3e-audio TPA3255 2x140W chip amp, which is just unreal fucking awesome.
https://www.3e-audio.com/amplifier-kits/tpa3255-2ch-260w/

i do expect these to last a lot more than 3 years, but i'm also pretty hard on my amp, moving it around a lot, running it outdoors, and perhaps most crucially, plugging & unplugging it direct to high current batteries, without the typical soft-start nicities a normal power supply would have. spark up the amp!