I bet a few of us remember AUDIO Magazine. It was one of my favorite reads. I want to refresh your memory that once a year in October AUDIO released their annual product directory. Pre-amps, amps, TT's, receivers you name it was there. If the manufacturer responded to requests for information. As there's a lot of interest in vintage audio this is real treasure chest of specifications. That piece of quad gear yoy just bought on ebay probably didn't come with any info. Go to the Radio Archives & select any year of interest in October and see what AUDIO magazine can tell you. Haha the one & only quad reciver I ever owned, a Kenwood 9940, retail listed for $974. I traded in a bunch of misc quad, graphic EQ box, Dynaco 120 stuff & paid abot $300.