I really never know when I'll get a chance to spin a couple sides so warm up time could be a factor.
Most tubes in a preamp take 20 seconds. And then about 1/3 hour to an hour to sound their best. By contrast most solid state preamps don't sound right for about a day; I found I had to leave my solid state preamp on 24/7...
As far as 'dynamics'... IME when audiophiles talk about 'dynamics' they are most often (about 90% of the time) actually talking about distortion, and if you swap the word 'distortion' for that of 'dynamics' the meaning of the conversation is unchanged. The brightness of solid state is caused by distortion, since the ear assigns a tonality to any form of distortion- its literally the difference between tube and solid state. But FWIW, the dynamic character of the music comes from the recording, not the playback circuit. If it appears to come from the latter, in all cases its because distortion is masquerading as 'dynamics'. If you want lower distortion, seek 'smooth and detailed'. Smoothness is a lack of higher ordered harmonics, detail is often associated with brightness but it really doesn't work that way! When its **both** smooth **and** detailed that's when you are really making progress.