I have mine mounted on my subwoofer box. Some will say it will break the amp.
It's a $55 walmart amp that pumps the bass enough to add some depth to the music and take the stress off my speakers so they don't have to pump the bass.
It's been screwed into the box for going on 4 years very soon. Nothing wrong with it yet.
Though if I had a wicked expensive amp I might be a little more cautious