from ARC to Pass ?

so, first answer is:
Pass X2 better than ARC LS25/II (in the opinion of jl35's friend, it's understood).
ok, thanks.
I've read many comments about the X150.5 power amp, and they all told about a very good amp, but I did not find comparisons with my venerable 100.2.
on the other hand, I've found very few comments on Pass X2, with my surprise: a lot of comments on X1, X2.5 and others, but few on X2, so I really don't have the faintest idea about what to expect.

question: so, daniele, why are you thinking of that combo if you don't really know about it ?
answer: I've always been attracted by Pass products, I always thought I would try some soon or later, and I've found that combo at what seems an honest price to me :)

First, I thank you all for your kind and interesting answers.
I know ARC Ref. 3, I often hear it play at a friend of mine's home. but here in Italy, where a live, I can find it (used) only at a much higher price than X2+X150.5 (say 4500€ vs 3500€).
One question: some of you advice using the X150.5 with a tube pre amp, maybe with an ARC preamp: I know X150.5 has a low input impedance; isn't it an issue with (most) tube preamps ? I guess it should be with ARC preamps, which 'love' high input impedance power amps.

guess 30k = balanced and 20k = unbalanced