PearlcorderS701 I was by no means trying to dissuade you from further pursuing the topic, but rather was trying to emphasize the importance of speakers and room acoustics.
To be honest, I don’t have any direct experience with DTS-MA because my Bluray player is too old

And I don’t want to spend the big bucks to get a newer player that has the same upscaling capabilities.
If I truly thought the sound difference was going to be night and day, I would have already made the upgrade, but to be honest, I just don’t see it as a good ROI for me at this point.
The article that anamorphic96 has provided really drives the point home that it’s a subtle improvement in an ideal listening environment. What can one honestly expect, if their room and equipment is not top-shelf?
I dunno, but I do know I have a laundry list of other things to buy and accomplish, that are going to make a noticeable improvement to my room and system. So that’s where I choose to focus my energies, but to each his own, I guess.
Where is your listening position? Is it near 38% or 62% the length of the room? Is it slightly off center to reduce width based modes?
How close are your mains to the front wall? Side boundaries? How wide apart are they? Distance to LP? Have you experimented with toe-in?
Are all your channels level matched? Distance correctly set in the receiver?
Are the early reflection point treated?
This is the kind of stuff I worry about first, then the smaller stuff.
IMHO the subjects I just mentioned are going to have a much bigger effect on how good your system is going to sound, in comparison to the difference between DTS core and core+extensions.
As far as speaker suggestions go, we’ll need a budget to work with, so figure that out first.
Are you absolutely set on having towers for mains?
Yes, you should probably stick with Polk, if you want to keep your current center.
SUBS: HSU, SVS, eD (elemental designs), Rythmik, Epik, Outlaw…I’m sure I’m forgetting some, but that will get you started.