Over the long weekend, I moved my Def Tech BP10Bs into the stereo (and spent the time necessary to fine-tune the placement), replaced them with the 8Bs in the HT, and am using the Polks as surrounds. The Polk sub is in the closet because both pairs of Def Techs have significantly deeper bass on their own (a full octave lower, in fact.) I think that the impression of "muddiness" that I had previously was false, and resulted from not being used to the extra extension. Within the range covered by the Polks (with sub), the DTs are every bit as clean and detailed. Their imaging is not quite as good as the Mirages, but certainly close. I think I am happy with this arrangement (for now, at least), and avoided spending more money.