Mine was cobbled together as well when I was a teen. In the late 1980s my older brother upgraded, and his Panasonic quadraphonic receiver went unused. I gave him $10. It had originally been owned by our oldest brother. I can’t even find it online. Basic, low wattage, similar to RE-7671. Got my hands on some EPI Microtower M-75 speakers from a garage sale for $25. It wasn’t a great setup, but I thought it was. Added an older Toshiba turntable, a new JVC cd player with my HS graduation money, and eventually a new JVC tape deck. I later bought a JVC receiver that matched my other two components, and upgraded speakers. The Panasonic, speakers, and turntable went to my girlfriend. Hopefully her or someone else is still enjoying them. I never did hear quadraphonic sound out of it, as none of my components were quad capable. By the 1980s, quadraphonic was just seen as an old fad.
Great option for an older stereo, and it’s nice that we can add this and Bluetooth so easily. My bedroom Sansui is controlled by the TV via a smart power strip with the TV plugged into the control outlet. Roku remote turns the TV on, easy peasy.