So the XP-25 is a keeper. I started playing with the loading, and this was an eye opener and what really tipped the scale... at 30ohms, there is a trough in the entire midrange with the A90 (4ohms internal impedance); at 50ohms (where I had it all the time), things were fine; at 100ohms things really came alive, and the Drum Record takes on a new life, vibrancy, attack, presence, and the bass is actually faster and tighter; at 160ohms things seem to be just right with every recording I have tried; at 250ohms the sound is too bright. I think I am going to settle on either 100 or 160 depending on the recording - would be interested to hear what Christian set his to. I have come to really appreciate the ability to easily change loading. Next up will be capacitance - though most claim it has no effect on MC cartridges, I fail to see how this could be: capacitance applied to the input is like affecting the inherent capacitance of the phono cable and the cartridge's own coils' capacitance, so it has to have some effect, even if minor.
I think the XP-25 makes a clear and convincing case, and its performance is really a tribute to all those heritage tube recordings. I would agree it's a bargain.