I always heard the biggest stress for most electronic equipment is the power-up stage. Some are designed better than other in this respect, but juicing em' up frequently will put more wear on components than simply leaving them on in an idle state. This would be true for most solid state, non-mechanical electronics -- say your console.
On my reel-to-reel tape machine, the motor is always spinning while tape is loaded -- even while not in play, so leaving that on all the time may wear down some mechanical parts... I like to turn it off, as opposed to leaving it run night and day...
Same goes for tube mic pre's and such... Leaving it on in an idle state all the time will lessen tube life to a degree (probably moreso than the power-ups), and will be throwing alot of heat out there... I'd probably shut it down overnight....
In the end it shouldn't matter -- gear is designed with these power-up tolerances in mind; it should be able to tolerate ebing turned on and off at least once a day, if not 100 times a day. Of course vintage gear and some tube circuits require a more delicate approach, the answer is likely going to be circuit-specific.
So basically, what I do -- I leave the console/converters/digital stuff on, and turn off the reels and any tube stuff... Just factor in the costs of leaving gear running, watch out for overheating, and be prepared to wait a bit on gear that has a \"warm-up\" time... Should you decide to turn it all off every night, you may lessen the life on some pieces of gear -- it's a crapshoot. But quite possibly the cost of repair will be more than met by savings to your electricity bill!
