ADS did exactly this with their Model 10 digital Acoustic Dimension Synthesizer. All you needed was a stereo amplifier and a pair of decent speakers mounted above ear height, aimed at the ceiling and placed behind the listening position. If you can find a copy, the owner’s manual provided a...
I bet that you could use a laptop for this purpose. I use Equalizer APO and peace on a windows laptop and it works just fine as a streamer. I think APO can process 7.2 channels (maybe more) if you need that.
Oops, I missed the part about the fried tweeters when I first read the OP’s post. That might be a problem, but maybe with patience a pair will show up on eBay or can be had from JBL
If you can find a nearby speaker repair shop, you should be able to get the surrounds for all of the woofers and mids replaced for less than $200. Once you do this and track down and fix the cabinet resonance, you should be good for another 30 years. If you have some money left over, buy good...
How about Robert E. Greene? He has an in depth understanding of acoustics and has always been interested in loudspeakers that carefully utilize room interactions.
I still have a pair of EPI 400s somewhere in my loudspeaker museum. They are basically 4 of the 50s in each box and are (reasonably) omnidirectional. Also known as the poor man’s 1000s! They are pretty with subtle brass trim and very heavy.
This guy has it pretty much figured out: https://gearspace.com/board/studio-building-acoustics/1385187-david-brancato-digital-room-correction-methods-using-rew-rephase.html
I’m using a Sanders Magtech which makes something like 900 Watts into 4 Ohms. It is loafing along in my system since I mainly listen to classical and jazz at sane levels