Like some of the writers above, I’ve never switched off the HV sources, even when going on vacation. Likewise, I also leave my tubed preamp and SS power amp on also, so take that for what it’s worth. I might mention that the first pair of A1s I owned (I think it may have been the first production pair out of the factory) was left on for about 30 years solid. After replacing the panels with the PX upgrades in 2007 or so, they’ve been left on again since that time. A couple of years ago, I experienced a power surge that knocked out both HV sources. Dr. West provided me with a new set, but with voltage regulation, and I believe that they actually sound a bit better than the old ones. Just my 2 cents.