Bruce,
That was a concern of many on the forum when I built the first HT cabinet. I have done several blind tests with differant freinds that have visited and out of a couple dozen listeners no one has detected any differance. I have placed as far as 20 " in front of the HT center and do not notice any change. As usual this is my expierence here in my room, so others may have differant results.

ROCK 'N' HAXIOM Theater