My family just bought out the company my dad had been working at for quite some time, and among a bunch of other random stuff we found tucked away in a storage area, i found these. I have them hooked up and they sound pretty decent, but being probably 30 years old they dont have a ton of output. The main unit has a radio on top along with all the volume controls, has the amplifier built in, and has a plug leading to the second speaker. the model on the back reads SHC-47F. the fronts read "crowncorder" and "duosound" were these a nice unit back in their day, or were they cheaper? what can you tell me about them?