Engls have great master volumes, the Fireball and Savage can even go down to whisper volumes. Diezel VH4 too. If you're into Marshalls, try to snag a JVM of some kind, maybe the Satriani version, those also have a good MV.
The major issue you're going to have with low volume is that tone suffers a bit. Got to have some air moving with speakers like V30s.
However, if you go with a speaker like an EVM12L, you are good to go. Those are able to reproduce tones at low volume as well.