I have been checking all of the X-Series speakers before they go out with an impedance sweep. This makes sure all the drivers are connected and all looks (electrically) as designed.
So far so good, but then I noticed when I shot a curve on the X-Omni that there was a slight cavity resonance that was indicative of insufficient damping material.
So I popped a woofer out and noticed a very thin layer of felt all around the inside of the box and nothing in the very bottom. This was not how I specified these to be made.

So I added a layer of fiberglass insolation all the way down the back side of the box from the port to the woofer. I stayed back about an inch off of the woofer.

I then shot another impedance curve and it looked fine.
So anyone that has or ever bought some X-Omni's from AV123 might want to take a look inside.
I went ahead and modified the pair that I tested for this customer, but I am not going to make these mods on all of them that I have. I simply can not afford to spend a lot of time working on these or making mods as I just don't make enough on them to cover my time spent doing that. These things are selling for only $325 a pair.
My best recommendation is to line them with No Rez then add some additional insolation or poly fill as per these pics. Then you'll have no cavity resonance and tighter and cleaner bass response to boot.
It also wouldn't hurt to check you X-Voce or X-Statiks and add a little poly fill or fiberglass insolation behind the drivers.