> Room IS very dead. But vocals still seem too muddy. <
Man, if your vocals sound muddy in a totally dead room I'm not sure what to suggest. Not that a totally dead room is a good thing, because a little ambience is often useful. But for straight ahead vocals that are close-miked, the sound might be dry but it shouldn't be "muddy."
What mike are you using, and what preamp or mixer? How far are you from the mike when you sing?