If your display, optical player, amplification, et cetera are all going to be coupled to your enclosure as I think you're intending, I'd definitely put some thought into dual opposed. That way the mechanical vibrations don't go straight into all of your expensive electronics. I know, they'd probably be fine, but it definitely seems safer to avoid the extra vibrations if you can. You could go out each side or one firing forward and one backward. They could share a volume of air or be separate.