The JTM45 will give you the tone you want but you will have to crank it so you’re back to the same situation again. I would try the studio classic. It’s worth a shot, it may just work for you. Another Marshall that might get you in the zone is the vintage modern. Or pardon my blasphemy (?) but Orange makes some great amps with master volumes and plenty of tone. The tiny terror is a beast through a 2 x 12 cab. You can make it sound like anything from mid-60s through 80s. Just a thought. I own Marshalls (JTM45, JCM800, Vintage Modern, SV20) and Oranges (Tiny terror, Rocker 30) and usually turn to the Orange amps when I need to play quiet but still want fat ass tone. It is true the marshals sound best when cranked. The good news is that you have plenty of choices. It wasn’t so back in the day.