I normally leave my solid state kit - pre/power, CD, DAC on all of the time as, particularly the power amp, takes ages (4-6 hrs) to warm up and come on song. However, I'm not sure what to do with valve kit - do I leave it on all the time and live with reduced valve life or do I switch off? If I switch it off, how long does it take to reach operating temperature ir is this valve/equipment dependent?