I have 4, thats right 4 Droid X's at my disposal. 1 is running leaked 2.2 (mine) the rest are running stock non-rooted 2.1.
I put the same soundfile on all 4, placed them side by side with the volume cranked to max on all 4 phones in every volume control.
Played the sound file back and it was completely the same on all 4 phones.
This whole "its louder on 2.2" is placebo effect at its greatest.