Class D amps are very efficient and there is really nothing that requires "charging" or warm up before playing well so I see no reason you couldn't leave them running. But if you do you don't want signal from upstream components to pop or squeal through the active part of the speakers. So you turn on from main amp, pre, any other sources, then speakers. Shutting them down is in reverse. I shut down all my components, including my X5's, at the end of a session, but I'm running tubes in just about everything (expensive NOS tubes at that) so I keep the hours down and turn them off. I let things warm up a bit when I start a session. I have a pair of all in Odyssey monos that I had to keep on at all times because those things had full rows of caps that would take a day before they charged and sounded good.