Funny how this began as a possible change in electronics was the question.
Not sure about everyone else, but your gear is not the issue. I did not survey your cables and accessories (I do like the Degritter!) and the choices you have made on gear are sound. No one here can really bash Dynaudio, PS Audio, etc.
It is a well-known rule of thumb that a room makes up 50% of the sound. Every room has natural resonant frequencies based on it's dimensions.
Yes, it is ratio and 13 x 26 x 7 measurements chime in with these results:
A room measuring 13' x 26' x 7' will suffer from severe low-frequency bass boominess (modal pileups), deep acoustic nulls, and midrange frequency coloration. Because the length is an exact double of the width (\(26 = 2 \times 13\)), the sound waves reinforce each other at identical frequencies rather than dispersing smoothly as they would in a Cardas Golden Ratio.
You could start to believe me by calling GIK Acoustics or ATS and giving them your room measurements and asking them.
You are absolutely out of your mind if you think I'll have another wall put up to make my room smaller!
A 10-foot wall is going to be a lot cheaper than the two subwoofers you are enlisting to try to deal with a room ratio that does not adhere to the Cardas Golden Ratio. You may fight the room 'til the end, and that is your decision, so maybe I should just not bother to help and let you go down that road.
You started this thread with the claim that the audiophile in me feels like there is more to be had. Hence, you have questioned your own setup. You followed that by asking where to go next? IMHO, a change in electronics is not going to get you there.