This is a simple modification to the Dual Power King amplifier from beavisaudio.com.
What's funny is that I have a motorboating sound from an LM380 amplifier and decide to build this dual power king and I ended up with the same problem. "Motorboating", oscilating.
That happens when you don't have a bypass capacitor between power and ground. So this one cap modification turns this dual power king into a usable amp.
With a tonemender as a preamp sounds really goood.