There are similarities and when I read about the XA25 it seemed strikingly similar to the F6. Nelson told me it is not... I take him at his word... even though he may be required to say that
...
And I agree that he did not have my speakers in mind with the design, although his second and third main criteria for those who may be interested do apply.
All I know is it sounds really good, so much so that I decided it is my main amp and the ARC is my change of pace amp. I have played it exclusively other than when Dan and Bill came over and we spent several hours comparing the two, ever since the amplifier was delivered earlier in the week.
I also agree with your point about the XA30.5. If one becomes available to me and I can afford it at the time I would probably jump on it, especially because of the balanced inputs and a tad more power.