Of course you can hear a difference. Equipment placed in between the speakers, like alot of people do, will have a big effect on the sound. The shape, height, material, closeness of components all affect this. This is an area that should be left empty to "tune" to your liking with room treatments, or even art or statuary. You can get good sound by accident with your rack here, but generally, it is not the best place. Unfortunately, it is the most convenient location since it requires the shortest cable lengths. Everybody does it! You might try this and find the sound gets worse. That is because the rack and components were reflecting the center image right to you, giving the illusion of the singer right there. Without a rack here you might need something else, something "controllable" to fulfill this function. I use Michael Green's "Room Tunes" to tune the empty space between the speakers and the sound is holographic, even with moderate components. Takes alot of experimenting with position to get it just right, but, WOW, when done.
