I want to thank all of you on this particular thread for all the advice, input and perspective you share with all of us who read and also chime in from time to time. A great times for this hobby. Anyway, I bit the bullet and got a pair of competent
subwoofers over the Memorial weekend, so I was a able to finally play with placement( which was luxury that I did not have with my LR built-ins) in the room.
I have not yet had time to run Antimode and Audyssey but plain room response and gain is looking MUCH better.
FR spread was from 67-93 dB, now 80-93 dB (built in vs duals screen shot) more over with placing one sub in the back of the room, and other keeping below screen, I tamed the nasty null around 42 Hz( front/back vs dual fronts pic). EQ and some more wall treatments should help some more.
All that with flat and usable extension down to about 8 Hz. It does sound awesome as well.Ran through some of my favorite music and movie samples. Gave new dimension to my HT, both for music and movies.
Only spoiler in this story that I did not go with PSA but gave a SB-2000 from SVS
a try-out as I nabbed duals for 1100$ in their outlet sale, will give them a try for next month or so and see if I would need to check the PSA. Must say I like the aesthetics of the piano finish with the rest of my setup.
Props to Tom and his character, to offer a detailed and honest advice, regardless of the make of the speaker/sub.