As for the coupling caps, it wouldn't dull the sound, but lessen that sharp SHING, BLING high end?
I'd probably want a change to both green and red, even the red is BLINGY, and sounds fizzy to me. It needs to be firmer and clearer.
Try an 10 band eq (or more) in the loop and see which frequencies you like boosted/cut out and take it from there.
Changing the coupling caps or even the plate->grid cap in V1a can help. They can really help in reducing the high end harmonics.