Re: Upgrade to ELX Towers for HT?
Yes, very noticeable. I had Def Techs before (procinema, I recall) and they were ok (but fatiguing at higher volumes and/or longer sessions, likely due to the metal tweeters). My first Ascends were S2's - big improvement over the DT's...moved to Towers / Horizon another step up, and just recently upgraded to ELX - another big step up. You won't regret moving to the Ascends.
What sub are you using? You may also benefit from a second or different sub(s) considering your room size.
* LG OLED65E6P, BenqHT2050A
* Anthem AVM90, Rogue ST100, VTV Pascal 7 ch
* Sierra Towers/Horizon (all ELX RAAL), S2EXv2 surrounds, HTM200SEx4 heights, Rythmik E15HPx2
* VPI Classic 1+ (VTA & Fatboy Gimbal), PE Eagle/RR, VAS NOVA, Soundsmith Paua, Manley Chinook, Bob's Devices SUT, SugarCube 1 mini
* Oppo 203 & 103D, EverSolo DMP-A6
* miniDSP Flex, Audiosensibility & Blue Jeans cables, Symposium & Isoacoustics, GIK
* For RDJ: Anthem MRX720, Sierra LX, Luna Duo v2 center, CXNv2, TBD