I have the corresponding Psss integrated (INT-30A), and I'm with Jazzcourier: the more efficient the better.
I love it, but it's just not that much amp, especially regards the lows; I here respectfully disagree with the many who say the smaller Passes are "more powerful than rated" and mate well with fairly low efficiency speakers.
Two that mine did not mate well with were the Gallo 3.5 (88db) and the Montana EPS2 (92db). They sounded pretty good, but the pairing didn't quite come together. Too bad, because both are very good speakers, and can be had at your pricepoint.
One that did work very well was the Vaughn Zinfandel (98db) an augmented full range design with powered base, which helped a lot. You don't see them much, but they, especially in a not-the-latest permutation, could be had used at your pp. Might be worth emailing Jim at Vaughn.
Btw, the Zins are not headbangers. You didn't state your listening habits, which would be helpful to advisers.
John