This fabulous NAD 7220PE receiver needed repairing, blown outputs, both! The 7020e was a donor, the boards are the same but the 7020e has some power supply regulation and other bits missing, for the Power Envelope circuitry, otherwise they are similar and share the same tuner section which is a separate board on top of the main amp board. Unfortunately the donor amp was missing casework and transformer when I received it otherwise that would have been repaired also but sometimes a donor board is very useful when making repairs. These NAD amps are well made and sound very very good, the tuner is also very good. However when the blow outputs they do tend to take quite a few other components with them, both drivers, the BD139 bias compensation transistor on the heatsink, several resistors, capacitors, and even the bias adjust potentiometer! - but not always depends on how the outputs are destroyed. After repair the bias needs adjusting, this is done by removing a solder link (one on each channel) and measuring the voltage across a 1 ohm resistor (there are two posts provided to connect the meter too on the topside of the board), when the bias is adjusted (30 millivolts on this amp) you need to re-solder and short the link again. You also need to set the DC offset using the other trim potentiometer, just connect the meter, set to volts, across the speaker terminals with speaker or a load connected, it should be as close to zero volts as possible (make sure you use the service manual to get the bias and offset voltages and tolerances, it also has the procedure clearly shown). These amps are well worth repairing they sound great and have plenty of current drive, they can drive almost any speakers.