[rockadanny]

what are you trying to solve via diffusion?

Without any treatment on the front wall there seemed to be some excess energy heard from up front at times. I asked GIK for assistance and they recommended the 6-inch Alphas, which have done the job in eliminating that excess energy. Most of it seemed to be mid-bass, which perhaps would have been resolved with just bass traps, but I just simply elected to go with their recommendation. Not so much because I might have had excess upper freqs. causing any issues, but because I'd read numerous opinions that some diffusion on the front wall was good to have. I like the resultant sound.

[rockadanny]

the best place for subwoofers to mitigate in-room bass peaks/dips is either in the corners or midway along the walls.

I agree, and had them set up per Floyd Toole's method at my previous home. However, I tried this in this current space and had a difficult time finding just the right locations. Perhaps due to such a low ceiling, or room dimensions? I about tore out my hair trying to get them optimally located. One day out of pure frustration I set them both up front, different distances from their respective side walls, and just listened - did no measuring. After all, there are $100k+ speakers with their woofers in the same box, right? So how terrible can it be to co-locate them? I liked what I heard and did not measure for quite some time. I eventually took some measurements and ... meh ... sort of OK. Since at this point I am completely satisfied with how it all sounds I am no hurry to start shuffling those beasts around again any time soon. They are set at 45Hz and produce good response down to 20Hz, so they're not covering much of the critical freqs anyway. Some day, when I feel more energetic, I may try moving them around again. But for now, I'm too busy enjoying the music. It all sounds so DAMNED good to me!

[rockadanny]

BTW, while I do on occasion listen to opera and some classical (lite) music, I do not listen to heavy-duty classical (i.e., Prokofiev). Nor do I listen to techno or rap. So perhaps this is why the bass response, imperfect as it is, sounds perfectly fine to me?