The speakers I had prior to these were Klipsch's, which are a fairly "bright" speaker. I haven't found the CM9's to be muffled on the high end by comparison. In reference to the other poster, I am running plain old 12 gauge speaker wire FWIW. Have you checked that the connectors used for biamp bypassing are in place and that the binding nuts are tight? It would be weird if that was an issue, but it somewhat fits with what you are describing.