I think that this speaker uses a Beryllium tweeter. I have heard tweeters of this type sound good, but this is not a material I would favor and usually dont like tweeters of this type. Experiment with speaker placement and tame your first reflection points to see if this helps. An acoustically bright environment with this speaker could be your problem. Wish I knew more about your cable. I dont think the Gryphon is your problem although tubes would probably help this situation. As Erik suggested, dont toe the speakers in one bit.