When I use my EP500 every day, I just leave it on. But when I know I won't be using it for more than a few days, I turn it off. For me that's generally on during the weekends, and off during the work-week.
I used to always leave it on, but then one night when my wife was out of town, I heard a low thump from somewhere in the house. It was like a heartbeat. After nearly pissing myself, I discovered that it was my sub. The really low-end sound was thumping very, very slowly. It went away when I turned it off and a tech told me that I just needed to unplug the EP500 for about 8 hours to dissipate a charge that had built up in the unit. Now I make sure to do that about once a year just so I don't hear that freaky sound again.
"Not throwing my hands up or my dress above my ears don't mean I ain't awestruck." Al Swearengen