My Quantum 4848 is running in a wooden 3U rack. It works fine (it's great!), but when it's on for a couple hours, even with no sound running through it, it gets rather warm to the touch. It's not hot or burning, but warm. I'm asking because sometimes I can have a creative session that lasts over a few days and I'm deciding whether to leave everything on over night or shut it all down. I just want to do what's in the best interest of prolonging the life of the unit.