I guess I am starting Boombox Mark II now.
I picked up a little Parts Express Blutooth board, just 50 watts X2 with no sub-woofer output.
It is now wired up and hooked to my garage speakers.
The best battery I have used so far is for my DeWalt 20V rechargeable drill, plays for hours.
I took a count of drivers I have available laying about, somewhere around 8 pairs, something must be able to work!
There are ideas rattling around in my head for what comes next. We shall see.
The amp is tiny, the size od a pack of cigarettes.
My speakers are huge, the size of a good sized man or perhaps a gorilla.