I don't leave my equipment in Standby mode. I turn off all of my equipment when not in use.
Just last night I watched three hours of Star Trek: The Next Generation (TV series), and my Amp 5 heat sinks were only warm to the touch.
I also have about 10 inches of clearance over my AMP 5 on my equipment rack.
My speakers are the Martin Logan Ascent i.
Maybe your speakers are drawing more current?
Also make sure not to block the air flow of either unit, and don't place the amp on the rug.