I play guitar and have played in and attended enough performances, both acoustic and electric, to have a good sense of the volume level of live music of different sorts.
With serious listening to acoustic music I generally try to match the level I recall of the real thing, with the exception of orchestral music--my room isn't big enough to handle that level. I listen to a lot of solo guitar and lute, and need to turn down the volume quite a bit for those. (It's unfortunate that even good sound engineers often amplify acoustic guitar too much at live concerts of popular acoustic guitarists.)
Fortunately, my Classé Audio DR-7 preamp has a system of discrete resistors for the volume control of each channel, so sound quality is not impaired by turning down the volume as it might be with potentiometers for volume controls.
As with orchestral music, I may not be able to match the volume level of rock music, so I just adjust it to taste. I don't have an SPL meter, so I couldn't say what the dBs are.

