Leave it on, and it'll be just fine...
I leave all my solid-state equipment switched on 24/7 [valve gear is always powered down when not in use], simply because I like it ready to sound its best, as soon as it's used, rather than having to wait half an hour or so for it to 'warm up' and perform optimally, but most importantly because experience has shown that it's likely to last longer that way!
I'm afraid that I don't buy the components 'wearing out' quicker theory, if gear is left switched on, as again the results of personal experience disproves it, or rather shows that the thinking is flawed. My Sony CDP and DAC, for example, have been powered up 24/7 for the last 6 years, with no problems whatsoever, and I'd expect the same to be the case in another 6 years. Previously I had a Naim system that was also left switched on for many years, with zero issues.
Quite simply, experience tells me that equipment is most likely to fail, at the point of switch on, due to the inrush of current, which stresses components much more than when they're being left to function in a steady state, and so should be switched on and off as little as possible. Of course there will always be exceptions to the rule, as components can suddenly fail for a number of reasons, but in general, electronic components are happiest simply left 'doing their thing'.
Therefore, folks, the only really valid reason for switching your gear off when it's not being used, other than when you're away from home for long periods of time (always a good idea from safety point of view), is to save electricity! :cool:
Marco.