I have owned the XA25 and dual AHB2 trying both mono and single stereo driving my Spendor D7.2 towers.
Even the single AHB2 was more than enough power. Although the Benchmark has lower distortion and noise I found the Pass XA25 more refined sounding overall and with a sweeter more pleasant treble.
The AHB2 had a more forward sounding midrange but somewhat flatter. The XA25 midrange was more spacious and literally soared into space.
Dynamics on the XA25 were fast and realistic. The AHB2 was actually too dynamic and hyper. You could be listening at a very low volume yet some parts of the music would become quite loud.
I just could not get the AHB2 to work in my system. The XA25 is a very special amplifier.