Pass Labs X1 vs. X2.5

Pass Labs "tubelike" I don't think that is accurate, either preamp or amp-wise.

I have an X-1 and it is very natural and dynamic sounding but you cannot get the tube like mids of a tube preamp. It has a little more detail and better bass than the 2.5 worth the difference if that is what the rest of your system can deliver and if that is important to you.

I have an X2.5 and find it very musical. Pass Labs has always been a perfect example of what good SS amps are all about. They are not in any way comparable to a tube amp. One thing you will notice with either the X2.5 or X1, is that the sound is quite "neutral" and the dynamics excellent. As Bigkidz pointed out, the X1 has a little more detail and bass, only because the noise level is lower and so you can hear the music more. But honestly, the difference is less than 5% if at all audible. The dynamics and sound is more or less the same. The X2.5 really sits at the point of diminishing returns and in the entire Pass Labs X pre-amp lineup represents the best value. It also depends on whether you like having one chassis or two. For me, I went for the X2.5 simply because I felt the difference with the X1 was too minimal to pay the extra dollars for; the single chassis helps as well because it conserves space. If I want to have a blacker background, upgrading the power cord would achieve a similar effect.