I hate to raise concerns, but here I go...you mention the bias meters moving with the music? I assume a fixed bias and small sensing resistor to measure current with Ohm's law?

If so, don't worry, nooooo problem! if it's cathode biased, the voltage change with signal could indicate an inadequate bypassing of the cathode resistance.

I must say, the chassis work is quite good. I really like the layout and appearance. Are the finals rigged as Triodes? U-L? Pentodes?
cheers,
Douglas