If you've ever listened to Live music, be it a concert, bar, night club, lounge. One thing that distinguishes live from a typical recording playback is what I call Music Presence. Even if the band sounds terrible, like at the last concert I attended at local arena, that Music Presence is still there.
IMO this Music Presence is not easily attained at lower SPL, unless you have a small room. This is why I listen in the 90-100 db range when I wanna Rock, to excite the room in creating Music Presence, which has a holographic quality.
Other factors that contribute to Music Presence making it more attainable:
Linearity of Bryston SST/2 amp
Transparency of pre-amp (SP2)
Upsampled resolution of the BDA-1
Quality recording
However there is an advantage at listening at moderate SPL. That is you can listen right into the heart of the music without strain on the ears. This makes it easier to follow the baseline, lead, rhythm all at the same time, which can be quite stimulating if the music's good.
