the 450 has a typical direct coupled output stage, which is more than likely where your problem lies. seeing that the unit has no blown fuses and is not in protection, the output transistors are not shorted. possible cause of severe distortion could be an OPEN output device, any other transistor in the amp, an open resistor, etc. if you're not comfortable repairing a direct coupled amp, you can send it in to us for diagnosis. the direct coupled circuits can be tricky. if everything isn't right, they're easy to blow up.