I find the Reference No. 32 to be a very composed, easy to listen to linestage. But, like most things solid state, it lacks a little bit of a "spark" of liveliness or vividness that comes with really good tube linestages. It also tends to not throw as expansive and enveloping a soundstage as some tube gear is capable of delivering. Whether these tube qualities are realistic or natural, as opposed to a coloration, I don't know, but I do like those qualities. Still, the Reference No. 32 is a very fine instrument.
Other than the two tube linestages I own, neither widely available, I have not heard any other in my system recently so I can only make rough comments about what is out there. I've heard really nice systems with Audio Note, Kondo and Shindo linestages, so these make good candidates, in my opinion.
In the past, I really disliked Audio Research linestages--they sounded thin, harmonically bleached and sterile to me. But, starting with the Reference 5, they have sounded better. I haven't heard them in a system I amp very familiar with, so it is just a case of no longer writing that brand off.