I was serious when I said I have yet to power it down since I got it and that was ~2 months ago and I do seem to remember the prvious owner saying he kept it on all the time to...anyone else, Nick?
EDIT: I just mine turned off and on and got a slight very small mid-low thud on power off and a very small mid-high pop when powering on, low gain and level at 10:00...i'm leaving mine on unless traveling.