I've had good results with Mesa Mark amps (Mark II, III and IV). If set up properly you can have very good tones at low volumes. A volume pedal in the loop can help as well, adding a 3rd volume control to fine tune (Channel Master, Global master and Volume pedal).
However, it's important to note that the amp settings would be different than if played at loud volume. I don't think you could use the same settings for both bedroom and loud volumes and get good tones in both by just changing the master volume, it would require some tweaking, particularly on the GEQ and both gain settings.
I think the fact that the Marks (at least until the Mk IV) have multiple gain knobs and volume controls is what makes it possible to create good low volume tones.
Also, as someone else mentioned earlier I think that 100W heads sound better at very low volumes than 20w heads. Fact is, a typical 100W head with 6l6s for example will not depend as much on power tube distortion as say a 20W EL84 amp. I had at some point a Mesa Mini Recto (25W) and a Friedman Runt 20 (20W) and for bedroom volume they didn't sound good compared to the Mark IV or Dual Recto. Their sweet spot would arrive at off course lower levels than with 100W heads but reality is even at 20W, that sweet spot was way too loud for bedroom practice. So when having both amps below their sweet spot, the bigger ones always sounded better. I would recommend the 20W heads for gigging in smaller venues and when portability is needed (they are much smaller and weigh less than full sized heads) but not for home playing.