JTM 45 circuit is pretty much an EL34 or KT66 version of a 59 Bassman. That which Leo stole from GE, Jim stole from Leo! It's a beautiful world.
I'd not put smaller trannies on a JTM 45 if I were asked to build one. I'd put some big old beefy sucker on there. Keep in mind, yes, you could downsize, but it's a tonesuck IMO.
If you want Marshall-esque tones at club volumes, get an 18 watt (2xEL84) Marshall clone. Some of them have a master volume in the design.
To answer your question, yes, volume dependent for those crunch tones.
Is it the EL34 tones you desire or just good crunchiness? You might want to think about going with a lesser powered tweed amp. Like a 30 watt Pro or Super.
You can really tame those a bit by using 5881 or 6L6WGB's in it. breaks up sooner than a JTM45 and has what I think is a much better tone. Just my old ears. YMMV