I owned both the XA-25 and XA 30.8 amps. I preferred the sound of the XA25 - more neutral but still sweet, incredible burst, dynamics and musical element separation.
The XA30.8 was noticeably more powerful as it should be given that it produces 160 watts / 4-ohms. It sounded too sweet and veiled in my system, a noticeable imprint on the music.