CoolGuitarGear is correct about using the guitar volume knob. Backing-off the volume is SOP when it comes to playing at volume, especially when playing through a NMV amplifier + gain pedal. MV amplifiers are for shit, as they compress the signal beyond a semblance of user control. You can back-off the volume knob, but there's no-way around the excessive compression that multi gain stage amplifiers generate. A lot of players rely on that compression and sustain, as it does wonders for making you sound better than you actually are.
For the accomplished player, nothing beats a good drive pedal + NMV Marshall, VOX or Matchless. Not that there aren't MV amps that I don't dig... The Marshall SJ, Wizard, Boogie IIC+ (w/o EQ) and Fender Pro-Sonic are great amplifiers for straight-in play. My favorite pedal + MV amplifier are the early JCM800, 2203 and 2204. I doubt anyone gives a f*** what I think... I'm just sayin.
Most metal guys are on 11 all the time, so the volume knob is more of an on/off dial. Not all, but most.