John, I wonder if you somehow ended up with an amp for the 350. I know you said it had a written 500 on the back but it could still be wrong. The 350 has half the power of the 500, so it makes sense that your dials are not in the same place.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70