Audioangel:
Most types of high-end audio electronics are best left on 24/7, and many manufacturers of high-end equipment intentionally do not include on/off switches on their equipment as a result. My Rowland preamp and phono stage cannot be turned off, my Audio Research CD3 CD player could not be turned off, etc. Without explaining in great detail why this is so (very short answers: turning equipment on and off damages it, and equipment left on 24/7 sounds better), only tube amps and true Class-A biased solid-state amps should be turned on and off. All other equipment, including tube equipment using small-signal tubes like tube preamps and tube digital-to-analog convertors, should be left on 24/7.