I ran the xp-15 in for almost 4 days straight. It sounded a lot better now and is a great sounding phono stage in the 4k mark.
However, the xp-25 is just better in every respect. Considering it is 2.78 times more expensive that I reassuring for anyone contemplating an upgrade.
Frank, The difference is pretty much what you said in a nutshell
Cheers