Sennheiser upgraded cable Cardas/Equinox?

I have several pairs of Phones. Senn 650's. Grado 325i, AKG 501's All of which I use with my ASL MG DT OTL MKIII HP amp.( tube rolled to good effect and AC cord replaced with Synergistic Research Master coupler)) and using RS Audio Illume' and Audio Art IC-3 as my HP amps connects)
Im looking to upgrade the cable on my Sennheiser 650's. I have tried the Moon Silver Dragon to good effect, but I still feel that even as good as this cable is... and its very good..( deep bass and dynamic midrange )I have a few issues with a lack of resolution and what I would call a "slight lack of tonal quality" in the upper mids.Not bad mind you..but I feel that I can get better still with perhaps the right cable upgrade. Not to mention how stiff and awkward this cable tends to be. I have not tried the Cardas or the Equinox cables, but am thinking of the Equinox...dont know where to find them however.

Can anyone offer an opinion or suggestion? BTW...Of course Id love to have the Stax Omega or Senn Orphius systems...but Im living in the real world with HP's :)

Thanks,
Ken