In my research the one that has caught my eye is the Pass XA25 but I am truly not sure how this would be with the ProAc’s. I would hate to buy this Blind.
As you may be aware, Reno Hi-Fi, which is apparently the leading Pass dealership in the USA and is wonderful to deal with, offers 14 day return privileges less only two-way shipping. Although they can’t sell a new unit (as opposed to a demo model or trade-in) to anyone who is within 100 miles of a different authorized Pass dealer.
I purchased an XA25 from them last year. It replaced the very well regarded 300B-based VAC Renaissance 70/70 MkIII I had been using for several years, and I haven’t regretted the change for one instant. Among the various published reviews of the XA25, I found that the one by Terry London (A’gon member Teajay), at hometheaterreview.com, characterized its sonics especially well.
That said, John Atkinson’s measurements of your speaker show it to have a sensitivity of only 83 db/2.83 volts/1 meter, which for its 8 ohm nominal impedance means 83 db/1 watt/1 meter. JA also measured the XA25 as being capable of providing 80 watts into 8 ohms (presumably after leaving class A at a significantly lower power level, given its 25 watt/8 ohm published rating). And I wouldn’t count on it quite being able to deliver 80 watts into your speakers, because their impedance is well above 8 ohms at a lot of frequencies.
The bottom line is that I would expect the amp to reach its limits when producing SPLs in the mid-90s at a listening distance of say 10 feet in a medium sized room. That will be more than enough for many listeners with most or all of their recordings. But if your listening includes recordings having particularly wide dynamic range, such as many well engineered minimally compressed classical symphonic recordings, I would have my doubts. I listen to a lot of those kinds of recordings, btw, but my speakers (Daedalus Ulysses) are rated at 97.5 db/1 watt/1 meter, and have particularly benign impedance characteristics. The combination has no trouble cleanly producing 105 db dynamic peaks at my 12 foot listening distance.
Good luck, however you decide to proceed.
Regards,
-- Al