Tweaks. Power, Resonance Control, and Acoustics. One place I might start is the Mapleshade Ionoclast gun. Zap all of your CDs and cables. You should notice increased clarity and retrieval of low-level musical information. Then get some Walker SST, paint all of your contacts, including AC power. Burn it in for 5 hours minimum. Then get some Mapleshade heavyfoot brass cone footers. Also place a few upside down on top of your transformers.
You might also try experiementing with slightly different speaker positioning as well as listening chair location. That can help change the sound, and it's free just given some time and effort on your part. Toe-in/toe-out changes the treble balance, "air," imaging, focus, etc. And closer/farther from the back wall changes bass balance. Also moving your listening chair out a few more feet into the room can likewise change the tonal balance and imaging focus for the better.