Sam,
The pots you see on the paramounts are hum balance pots, not volume controls. That said, I did borrow a local guy's (paswen) paramounts which had volume controls on them and they were fairly easy to get balanced, though I'm pretty sure I wouldn't want to use them like that forever. Stepped attenuators, maybe, but not normal pots.
HTH,
Jim
Jim Rebman -- recovering audiophile
Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).
s.e.x. 2.1 under construction. Want list: Stereomour II
All ICs homemade (speaker and power next)