Tvad, do you still want to hear a pair of Clayton's or is that water under the bridge already? If you do still want to hear some, I can try and hook you up. Unfortunately, the mfg is in St. Louis and the main distributor is out east. If you ever get to Michigan, you are welcome to hear mine.
Regarding sonics, IMO, my M300's are richer, more natural, and more musical sounding than my former DNA 500 (which was a very nice sounding high power AB amp); and they are more powerful (300 vs 100 wpc), more extended in the treble, and have more detailed bass than my former Lamm M1.1's, although they are a touch less dimensional than the Lamm amps (tube vs. no tube). I would like to compare them with Lamm's M1.2 Ref. amps. The Clayton's do a nice job of passing through what they are fed, with maybe just a touch of flavoring toward the warm and rich side of things. They sound good upon turn on, but best after they have been on for an hour or so, high bias sounds better than low bias, and the M300's do more of everything the M200's do (I owned both). Unfortunately, I have no direct comparison experience with the XA.5 amps.
Regarding sonics, IMO, my M300's are richer, more natural, and more musical sounding than my former DNA 500 (which was a very nice sounding high power AB amp); and they are more powerful (300 vs 100 wpc), more extended in the treble, and have more detailed bass than my former Lamm M1.1's, although they are a touch less dimensional than the Lamm amps (tube vs. no tube). I would like to compare them with Lamm's M1.2 Ref. amps. The Clayton's do a nice job of passing through what they are fed, with maybe just a touch of flavoring toward the warm and rich side of things. They sound good upon turn on, but best after they have been on for an hour or so, high bias sounds better than low bias, and the M300's do more of everything the M200's do (I owned both). Unfortunately, I have no direct comparison experience with the XA.5 amps.