I have mine over a clarion the heat hasn't been a problem and I didn't really notice anything unusual until I went on a 7 hour drive when I got to my destination I pulled out the empeg and it was scorching as was the clarion. I would very rarely drive for that long so I'm not going to worry about it.

although I have been considering taking out the clarion and just installing the empeg tuner because I just think it's too ugly