This is similar to most electronics of the past few years. You'll notice most electronics don't have an OFF switch. They have a STANDBY switch. This is too allow a very low amount if electricity to keep components warm with in the electronic device; to avoid a "cold start" when you push the power button.
Think about it this way. When does a light bulb blow? Usually when you first turn it on. It's the sudden surge of power that hits the cold filament that make is blow. If you could only have a few watts keeping the filament warm, they would last much longer. But Light bulbs are so cheap; it doesn't make sense to do this.
However you plasma TV, HT receiver, or in this case EP500, are much more expensive to replace.
As a general rule you should never use a power bar to turn on and off electronic components.
If you are not going to use the EP500 for a few weeks, unplug it. However if you plan to use it a few times a week, keep it plugged in. The cost of electricity is minimal compared to the cost of a repair bill for the components.
Paul
