No. I do not leave my equipment on all the time.
I have noticed that my equipment sounds wonderful with about 30-45 minutes of warm up. So, when I come home from work I turn everything on, do my chores or what not and then when its time to sit and listen, I'm good to go.
Other reasons why I don't leave them on:
1. Energy waste.
2. potential for fire hazard. Other than my refrigerator and wine coolers, everything else is off. Leaving equipment powered up when not at home is asking for trouble.
I have a Krell KBX electronic crossover with internal circuitry specific for my Martin Logan Monolith III speakers. There is no power switch for the crossover or the external power supply. Therefore, unless I unplug it, it is always on. One day I came home to a house filled with a burning smell. It was the crossover. a couple of components failed and were cooking. it was a fire waiting happen. This was a lesson learned for me.
All of my low level equipment (crossover, pre-amp, DAC, CD transport, Turn Table power supply, phono stage) are all plugged into my Transparent Audio conditioner, which is in turn plugged into a dedicated line. My amps have their own dedicated lines. So, when I'm done listening, I turn amps off, and unplug the power conditioner.
When I leave for more than a few days for a trip/vacation, I unplug everything.
Jaw dropping differences for high end equipment are quite rare. subtle differences yes, but jaw dropping, not really. So, when my equipment is warmed up, I am very good.
enjoy