I have 2 both in great shape both 100% working. Next to impossible to find these are rare and very good little amplifiers. Oddly enough I never opened them up to see what makes them tick. I dont know if they are discrete, chip or mosfet but they WORK. I have powered my center bridged and surrounds 2 channel (stereo) with them, and they shine with a set of professional Yamaha NS-10m Studio Monitors on the computer (They turn themselves on and off too!!!!) If you are very serious about them 570 657 1268....Justin......I wanted 1 more myself but for the right price ANYTHING is for sale and I can start over.