Finally have the chance to install the rectangles. I have only purchased a set of four adapt rectangles to replace the horizontal seams in my room. Based on the advice from Nathan, I installed 2 rectangles in the front of the room, between the front wall and the ceiling, and one rectangle on the left and right side of the room. I retained the seam at the back of the room. I could not install any rectangles at the verticle intersections of the front, left, right and back walls due to the existance of various furniture and a door.
Four adapt triangles were installed first as previously stated. The rectangles brought a similar kind of improvement, only magnified. Details of music become more apparent, you don't have to find them, they are all there in front of you. There is a new level of coherence and togetherness that wasn't there before. Instead of the vocal being louder than the instrument so all you hear is the vocal, all other part of the music is catching up now and all of them is right in front of you at the same time.
The rectangles have a large effect on bass - the drums, and bass strings are more powerful and with a lot less overhang. The overall presentation is more dynamic.
Lastly, this improvement works equally as well on home theater. A whole new level of experience of being there in the movie. Overhead thunders, sirens, and explosions are emerging from space, instead of the proximity of the speakers.
All in all, the improvement brought by the adapt treatment is much better than the same money spent on equipment upgrade. I would highly recommend anyone who is thinking of upgrading their equipment to get the adapt treatment first.
Only if I can fit 4 more rectangles at the vertical corners, may be I can convince my wife to move the furniture around......
Mike