I have vintage second system which at its heart has a Roksan Platinum PR15B & ST1308 Pre and Power. If it were not for the Auto Signal Sensing system where it powers into low state until a signal is detected, it would cost me around £180GBP per year to leave idling, in reality it costs me about £30GBP.
However, I never leave my main system EAR Yoshino 912 all tube/transformer driven Pre Amp on, it has some natural designed in functions that make it inherently a soft start system and neither do I leave my Tube Power amp powered on either fully or standby. Tube life and component heat stress is a far more important factor for me and more than out weighs any unconvincing benefits sonically of keeping everything in a fully powered on state. It has a relay bypassed soft start system too.
Typically my pre amp reaches optimum 15-20 minutes after switch on, the same goes for my power amp. I use the REL’s standby system which works well and I have heard it helps modestly to preserve their amplifiers in the same way as the auto low power state for the Roksan Pre & Power in set up 2.
So when I want to listen to my main system. I switch the system on 20 mins before I start listening usually with low level signal playing from the streamer.
I leave the power supply to the Lumin X1 powered on which is again in the region of £30GBP per year.
So I feel I have struck a reasonable balance of system preservation and reaching sonic sonic stability and optimum performance states, without taxing my system from cold and having to wait too long.