BTW, Do you know when solid state amps were started to be manufactured over tubes?[/QUOTE]

It was in the late 50's early 60's. Actually the process tooks quite some time. At first many "hybrid" amps/tape recorders/record players etc. began to appear. These were devices that had both transistors and tubes. As transistor technology became better, more and more tubes were replaced with transistors until finally, there were no tubes at all. I had several reel to reel tape recorders that had both tubes and transistors. I also have a 1959 Seeberg jukebox that has one or two transistors and the balance tubes.