ARC Ref3 vs Cary SLP 05

I recently spent about 1 week with my friend's slp-05. I thought is was very detailed, excellent bass, nice mids, but I could not help but notice it was "hot" sounding, ie tipped up in the trebles. I would not call it harsh, but it called attention to itself. Now, I have heard this same preamp in his system (we have identical speakers and very similiar digital front ends) and I have not noticed this with the treble. Instead, it simply sounds like a synergistic match to my ears...
I think it is clear that there may be a compatability issue with the SLP-05/Pass amps...

(also I have an LS15 on hand and it is a great match with the Pass. The tipped up treble is not really a trait with this match.)

I forgot to add, He is running a Mc402...

MMitch7711, I think they were plain old Cary spec stock tubes...with plenty of life.
I don't have much experiencing tube rolling, but it seems like a nice way to tailor a particular piece to one's liking, though it may be hit and miss along the journey (yet another symmetry with this crazy addiction)
D