G-7000 distortion question.

[cfinchrist]

I recently picked up a Sansui G-7000 which sounds pretty good at low to moderate volumes. When I play it louder (meters barely hitting 10 watts) there is a slight distortion (grainy/hashy) no matter what speakers I use. I already had it gone through by a tech who adjusted amp bias and dc offset supposedly. My G-5000 does not sound that way, so what is the likely culprit with the G-7000 distortion?:scratch2:

 

[EchoWars]

The unit needs to be fed a sine wave and scoped (and monitored with a distortion analyzer) while feeding a dummy load to even get a clue. The possibilities are endless as to the source of the problem, but regulated supplies are always the first suspect, and unregulated supplies the second.