Those service centers have the ML schematics and parts. Pyramid's owner, I believe, worked for the old Mark Levinson brand. Any one would be a far better choice than finding a repair center on your own.
When an amp causes a popping sound it's DC current going to the speakers. If it's preceded by smoke it's most likely a shorted output transistor causing nearby components to burn. Tracking down the problem without a schematic is very difficult.