Magnepan MMG or something else

You need to identify what aspects are contributing to your lack of involvement, otherwise this is just a crapshoot. Is it timing? Is it a lack of tonal richness or image density? Or a lack of dynamics? Involvement may be subjective but that doesn't mean you can't identify what's causing it, and it would make this post much more helpful and productive.

Some good advice here, and I agree with Soix -- you need to tell us more about why they aren't involving, if you can put it into words.

As several have said, placement is key. In particular, they want to be out from the front wall behind them -- at least 5', the more the better.

Also, that wall should be reasonably flat so you get a good image.

Agree that the bigger ones are improvements over the MMG's, but you can get much of the way there by mounting your MMG's so that they're standing vertically and raised off the floor, with the driver centered vertically on your ears. Try it with some boxes first. It makes them image like the big ones. Then there are various options for stands. Raising the up and vertical will make them image like the big boys, almost.

Finally, adding the DWM woofer will extend the bass. You have a relatively big room and you may not be getting the low frequency foundation you need. The midbass region in particular is crucial to a sense of heft and involvement.

The OP's last response was over four years ago. I wonder if he's still reading these replies.

Good point Rodman!

I'm sure he has either worked it out or punted by now.

Lots of prople still read these for the collective wisdom imparted.
Here's one, if you have MMG's run, do not walk -to beg, buy or borrow Analysis Plus Oval 12 speaker cable, this is THE cable for these period.