DUDE! Enjoy that amp. Get to know your amp first before you start doing anything to it. One thing that helps me tremendously in the volume department (reducing volume and enjoying fantastic tone) is to plug in to the lower output of either channel, EQ to taste, favorite boost/OD, set the PPIMV at 50%, volume at 3:00, and wail away. Do not bridge the channels.  With the PPIMV anymore than that it seems to suck the tone and all you get is pre-amp tube crap. This set-up seems more earthling friendly and won't kill small animals. Also, I think one speaker for the house is better than two.

FWIW - I am a new JTM 45 owner as well. On my amp when jumping the channels going from high treble (1 - lower input) to normal (2 - upper input) gives the most bass response with the guitar plugged into 1 - upper input, I just turn the bass to zero. If I jump high treble (1- upper input) to normal (2 - lower input), guitar plugged into 1-lower input, then I can use the bass control knob. Also, if I do not jump channels at all the bass can be EQ'd easier.  I am playing stratocasters, s-s-s.