Hi-Fi Chambers
Looking at your room, I'm confused about your calculated volume of 28,000 cu ft as the photo is of a room that appears to be a fraction of that volume! With what appears to be a fairly conventional positioning of speakers and listening position, I'm interested in your choice of omni-directional speakers.
I'm intrigued because I was seriously contemplating omnis myself, as they should be the obvious choice in my semi-circular room with kitchen and dining areas behind the centrally-positioned speakers.
I recently visited showrooms to listen to German Physics (probably my preferred brand) and MBL omni speakers. I was impressed by their very flexible listening position feature, but in both cases, imaging was not good compared with my Avantgarde Duo XD horns at the main listening position, though of course the horns have a very small sweet spot. Because of my 945 sq ft floor area, I was interested in their Borderline speaker, though the showroom could only demo the HRS-130. I'd dearly like to try Borderlines in my own room, but I doubt there's a UK dealer who could arrange this!
I do have a back-burning plan though, that might give me the best of both worlds. To get a pair of GP's PQS-100s (basically the DDD units on their own (plus XO) and good above 120 Hz) and to devise a circuit so I can switch between the horns for mid and top (when listening on my own at their small sweet spot), or the DDDs (when listening in the areas behind my speakers), but in either case sharing the Avantgarde's bass enclosures for sub 140 Hz frequencies handled by their twin 12" drivers. If I could switch between the horns and the PQS-100s (with a massive adjustment in woofer volume to cater for 107 dB sensitivity compared with 84 dB), this should provide great sounds at all listening positions. Dirac Live and DL Bass Control (included with my new electronics) could adjust for more subtle differences in frequency responses after switching the upper frequency drivers.
PS - I did purchase a pair of Martin Logan 13A Expression speakers that I hoped would replace my aging AG Unos from 2002. They sounded fantastic at the showroom and they enjoy great reviews, but they seriously disappointed when placed in my own room, despite the efforts of Anthem DSP. I concluded that, without a wall behind them to harvest some of the 50% of their energy projected backwards, they were unsuitable and had to be resold soon after purchase. Omnis shouldn't have that difficulty of course and neither do horns. Peter