Are you saying that if the target is 85db peak listening....and one preamp gets you there at 9 o'clock and another at 1 o'clock, the playback with the 9 o'clock preamp will not be as dynamic as the one with the 1 o'clock setting?
The short answer is YES!
85dB is way low, by the way. We aim for at least 100dB peak to leave plenty of headroom. Plus, with speakers like the JTRs, we look to create a physical impact with the bass. That takes more like 110dB peak, or even 120dB in some systems.
Regarding the volume setting, it depends too much on the system as a whole to just provide a rule-of-thumb listening level for a given volume control position, but the more usable range the better, without being starved for power at the max, is what we're seeking.
So, the ultimate would be that you'll never want to go higher than the max volume, but you won't typically be listening at the bottom range of the volume control, digital or analog. When we go digital, we start talking about effective bits and such....