Muffled vocals

I have positioned my speakers every way imaginable and I just can't get the vocals the way I want. They're centered, but they seem like they're in the background.  I want them more up front.  I've tried various toeing methods and room treatment but they still seem a little muffled.  My equipment: Lyngdorf TDAI-2200 integrated, Marantz CD6006, Tyler Acoustics D-20, Anti-Cables, Audioquest digital cable.  I know the recording can have a lot to do with it, but Steely Dan's Aja is known for the recording quality and Donald Fagen is in the back.  My terminology no doubt betrays my lack of sophistication when it come to audio, but I know something's not right.  Any suggestions?