A 10 watt sub is way underpowered to be enclosed completely inside a 3/4 solid thick walled MDF box. I have a similar cab but he sub is a 10 inch speaker with a 150 watt or so amp on it (it's a set of Logitech Z560's). Can't remember the exact spec on the sub output but it's supposedly a 400 watt system that includes 4 speakers and a sub. Of course, that 400 watt spec is "music power" which is vastly different than RMS which is the only meaningful way to measure output power of an amplifier.
Still, I would think the amp for the sub would still be pushing at least 50-75 watts RMS which is enough to vibrate the 3/4 inch MDF cab it's sitting in. No complaints about the sound when playing music but I have not really played music on it much. So I am thinking of taking these overkill units out of the cab and making an mp3 juke with them, replacing with a cheap speaker set that will do the job for games.
Unfortunately, I don't have any suggestions for making your sound better except "get a bigger sub" or "place the sub outside the cab where you can hear it."
Good luck
Bumble