To my needs experience, solid state stuff needs much more warm up time than tubes stuff which sound already fine after a few minutes of warm up.
Tube Preamps Should Have This Feature
So it's late or you just want some casual listening for a short time. "Should I fire up my tube pre for 30 minutes?". My answer is "No". Why not let me flip a switch (or push in the volume control) to put my pre into "bypass" mode? Bypass would, effectively, convert your pre into a passive device, keeping the tubes dark.
This sounds useful to me.