Lots of Pass fans here. I haven't heard the XA30.5 or XA 60.5 but I had the Aleph 3, 5, 2, XA 160 and now have the XA 100.5. Sorry if this post deviates a little from the origial question.
With the exception of the Aleph 3, all of these amps drove my Eggleston Rosa which is 87dB, 6 ohm nominal and 4 ohm minimum. My room is 16.5' X 15.5' X 7.5' for a total of 1918 cubic feet. I find the XA100.5 to be by far the best of the Pass amps that I have had in my system. Having gone from 30 watts to 60 to 100 to 160 and back to 100, I have concluded that in my room with my speakers the extra power made a very noticable difference, especially the extra current and doubling of power with the halving of impedence of the XA.5 - 200watts at 4ohm load.
The impovement is in greater ease and flow of the music and much better grip and impact of lower frequencies. The noise floor is lower and focus/staging are better, but this is because of the improved circuit, not power I think. Also everything became quicker. If I could have afforded the XA160.5, that would have been even better at 320watts at 4ohms. The Egglestons love power, even in my small room. I listen at an average 85 dB with peaks above 100dB.
Having said all that, I bet the XA30.5 with a 91+dB efficient speaker would sould incredible. Hope this helps and congratulations.
