First off you're very welcome for help. I'm glad that worked for you at least for the time being.
Now lets try to address the speakers and AVR recommendations.
AVR - Yamaha RX-V379 or Denon AVR-S510BT both currently at $280 new but both can be found refurb ($220 and $190) for less. Entry...
A new AVR would be the best solution as you're just going to keep running into issues as you try to add in modern sources.
I think for now just put your AVR into some kind of simulated surround mode (soundfield) like a DPLII if it has it. I'm assuming it does but without a model number I...