Ozzy...
My experience with the Hologram D has been that the frequency extremes are handled in a way that gives one the feeling that your amp has unlimited headroom... top and bottom. Every cord prior to this had some region that tended to be emphasized over the others... and most often, as you suggested, suppressing the upper frequencies.
A slight emphasis on mid-bass was something I thought was brought on by my room, but it turned out to be the previous cord to the cdp. The Hologram D provides a more balanced, top to bottom response... and completely free of grain with the typical Tesla dead quiet background.
Another thing that impresses me is the amount of detail and nuance that can be heard at the frequency extremes. Somehow the cord does this without overly sharpening the focus. If the top end in your system is sweet, then it stays that way, but with much more information. No digital glare, no digital fatigue.
Don't mean to butt in, I'm just very enthusiastic about having discovered the Tesla line. I'm in all the way.
