Wife was out of town this weekend, so I did some EXTENSIVE listening and acoustic panel experimentation. I was surprised to find that the tall silk trees I placed behind my Summits, alone, are better for overall acoustics than the wall-mounted 2' x 4' panels! Playing my standard "test tracks" compilation, and changing no other variables, I listened to 4 different configurations...
1- Summits alone, with NO panels or trees- My baseline setup. Slightly boomy bass, smeared imaging, and slightly shrill highs.
2- Summits with 2' x 2' angled floor panels and 2' x 4' wall panels- Imaging and bass much improved, with a deeper soundstage, but highs slightly rolled off.
3- As above, with addition of tall silk trees for added diffusion- This was the first time I really got to compare the effect of the trees/panels combo... the highs are really too rolled off, and the soundstage lacks "presence" due to the loss of any reverb. In other words, sounds very overdamped.
4- Summits with 2' x 2' floor panels (no wall panels) plus trees- Superb imaging, tight bass, and natural sounding highs. The angled floor panels do a great job of bass trapping, without absorbing the highs, and the trees add sufficient diffusion to minimize rear wave cancellation effects, while preserving tight imaging, and the "presence" of "live" sound. Quite impressive!
So, I ended up with the two 2' x 4' panels to place elsewhere. I put one behind my component rack (left side), and it yielded a more centered image by balancing the (right-sided) open walkway on my front wall. I should have considered that anomaly all along! Not sure what I'll do with the remaining 2' x 4' panel, but might cut it to fit behind my low console cabinet. I'm really glad I got both 2' x 2' and 2' x 4' panels, which allowed such flexibility!
So, for those of you entering the realm of acoustic treatments, don't sell short the idea of using silk trees for back wave diffusion along with judicious use of acoustic panels. Not only are they decor-friendly, but they work!