Pitt

I just had a 7.1 system set up yesterday with all Klipsch. In the room is berber carpeting where I have F2 front speakers and the sub 12 sitting on the carpet, the rest are a center channel and wall mounted C2's. The installer is coming back in a couple days to tweak anything I am not happy with regarding sound. I don't know if it's my imagination, but the speakers on the carpet especially the sub seem to have a slight dull sound, not that they sound bad. They do sit on the small legs, but I am wondering if there is anything missing on the set up, or would placing something under the speaker or legs help to pronounce the sound.