I would start with dinner and a TWO nice bottles of wine.
I’d move from there to a second dinner if need be and possibly a male or female escort. Just depends on how set in her ways the wife is.
THEN fix the room, it is 50% of the sound and 1/10th cost to fix. Besides it might make her happy for once, sometimes that’s all it takes.. :-) 3k tops.
Take a few quid and treat yourself to a dance lesson or two.. Put on a G-string and go roller blading.
Buy some chickens..
Re-Roof the outdoor speakers and air the tires.. There Big ones.. :-)