Say I bought a 6505+ 1x12 combo, or a ValveKing 1x12 combo, or a Classic 30, or a used XXX combo, would putting a volume pedal in the effects loop allow me to crank the amp to get that awesome high gain, extreme metal, tube tone but then turn down the volume pedal to get low bedroom/practice volumes, or is that just a stupid idea?! You see, I need an amp that will be able to handle bar gigs, yet I need something that I can practice with in my room at home too. So far I've tried the 6505+ AND the ValveKing, but my volume would need to be at 0.5 or 1 at home, and those two just didn't sound that good to me at those volumes...

Alternatively, would this work with a full stack either?

Or is there any other way around this that anyone has found? Should I be looking for a 15w tube amp instead of anything over that? Would a 15w tube amp be loud enough to play bar gigs with?
A volume pedal in the loop does exactly what the master volume knob on the amp does, so it's pointless.

A 15w tube amp will handle bar gigs, but don't expet much clean headroom, depending on how loud the music is you play - if you play metal, the clean headroom might not suffice (though volume will).

Personally, I think a Classic 30 sounds just fine at low volumes.
I'm not sure bout the volume pedal, but what I think u would want is an attenuator, or an amp which you could alternate the wattage, like the tiny terror