In all honesty, the PRS amps really do seem to have a pretty darn good master volume from my experience with the two I've owned (PRS Original Sewell 50w and the customized "Gain Monster" 100w 2-channel H), but if you're looking for whisper volume with great metal tone out of a 100w high gain amp, I'm not entirely sure that's the most realistic hope to hold.
All of that being said, I'll be jamming mine in a basement so I'm hoping the master volume is as good as I've seen on Doug's other amps. If that's the case, it should definitely be getting a lot of use at home, but likely when the neighbors/wife aren't home since the 100w 2-Channel H I had was pretty loud for the high gain side when things started to sound "better" on channel 2, FWIW.
I'm also hoping to try my hand at profiling the amp at volume at a buddy's house with my Kemper so I could run the Kemper through my CLR at lower volumes while still getting that same tone when I'm at home and the wifey and pooch are around... Even with the profiles, I'll still be keeping the Archon around as while I love the Kemper, I still feel there is that little something extra you get from tube amps (besides hearing loss haha) that is hard to replicate without going 100w tube amp into a 4x12 guitar cab!