My Marantz is rated for less than .5w in standby, much as Lovin' just posted .
I agree with your concerns in general, but there are better ways to address them...
Now if you are the guy that unplugs EVERYTHING you aren't using from TV to Nightlight, and you NEVER leave your phone charger plugged in (which draws current even when a phone isn't attached), you've changed to the most efficient LED lightbulbs that you only use as absolute necessity, and your electricity meter NEVER spins except for when your fridge is running, then sure... unplug your AVR.
(Now of course this already assumes that you are a vegan that only rides a bike, doesn't smoke or burn a candle, or use a fireplace or start a campfire... I should probably stop now... just feeling frisky... sorry.)