I have a leather chair the back is fairly low. But most of the time I sit on the edge and forward so the chair doesn't really effect the sound. However at times I lay back in the chair and my ears are below the seatback. It does effect the sound, one: as I sit forward I am closer to the speakers and two the seatback does effect reflection but I am further as well. At the end of the day I find that comfort is a major ingredient too. That levetation suggestion does souund good except for when you lose concentration, drop and the record skips!
