I am in the midst of something of an experiment. After living with a solid-state Audio Research LS3 preamp for 19 years, I have taken a plunge and purchased a McIntosh C2300 preamp, which is a tube unit. I was, admittedly, influenced heavily by all the praise for this unit on another forum and, quite secondarily, a review by Harry Pearson (formerly of The Absolute Sound). I am basically a solid-state person, but was intrigued by the 2300.
I listened to the 2300 in three sytems before buying one. I've had the 2300 in my system for a bit over a month now, and have noted some things. With the 2300, I have noted an openness to the sound (midrange in particular, which is where most of the music is) that the LS3 doesn't have. I can actually make out more of the lyrics in Sting's "Fortress around Your Heart" from his The Dream of the Blue Turtles LP. I have heard details here and there I didn't notice before in various recordings. There is a bit more of an "in the room" quality to the sound. These are good.
What the LS3 has, by comparison, is a less open sound but a somewhat tighter one, and there is more weight to lower frequencies, more dynamism. The bass has more authority. The 2300's performance has improved as it's been used, but the LS3 is still better at this. I've heard this is one of the classic differences between tubes and solid state.
For DVD and Blu-ray, the gap is much smaller, and as noted, the 2300 has improved as time has gone on. Watching The Avengers is more than satisfying, but the LS3 still has a bit more oomph. Watching Rick Wakeman's solo performance in Yes: Live at Montreaux The leading edges and transients of keyboard notes were more prominent (and initially distracting) with the 2300, very different from the LS3. But then, the low synth notes were more articulate with the 2300.
This is all with the 2300's stock tubes. Many 2300 owners like to swap out those tubes for better ones. I will be trying that, as I'm replacing the stock tubes with another brand I researched (JJ ECC803s) to see if the 2300's dynamic performance improves. Then, there are Gold Lion tubes, considered by many to be the best ones for both audio (especially with Mac gear) and guitar amps; they'd be next. If, after one or two tries, things don't improve appreciably, I may well sell the 2300 and go back to my LS3, giving up the 2300's benefits, or go for another solid-state preamp, probably the McIntosh C48. Or I may become content over time with what the 2300 has to offer. I'll see.