Heres a Toshiba SC-410 quadraphonic adapter. This is an early type of quad device that is essentially an amplifier for the rear speakers only. It hooks up to your normal two-channel stereo, I am told, through the tape monitor loop inputs and outputs, with your existing stereo providing the normal signal for the front speakers. Theres two sets of speaker outputs on the back, but this isnt for all four channels... the second set is just a duplication of the rear signal... most likely the second set will never be used. The unit powers on and I did put a signal through it to test it. I heard an out-of-phase presentation of the music I was playing, which is exactly what this thing is supposed to do. Please check internet boards for help in hooking this thing up, as pretty much everything Ive learned is what Ive typed here.