If it's just the upper mids that are bothersome and you're otherwise happy with what you're hearing, another way to go that may work and potentially be much cheaper would be to try some other cables and interconnects. Nordost are great to be sure, but even in the context of otherwise very good systems they sometimes don't convey enough tonal density or weight or can be a little too revealing in certain areas. If it were me, before dropping big coin on a new source I'd try to audition some Acoustic Zen Silver Ref. II interconnects and Hologram or Satori cables to see if they might yield improvements in the upper mids without sacrificing in other areas. Obviously there are lots of other brands you could try, but I only mention AZ because I'm most familiar with them and think their sonic signature may work particularly well in your situation. If it doesn't work at least you can go forward with more confidence you're doing the right thing.
Final thought -- if you have a Bel Canto dealer nearby maybe try the CD1 feeding a DAC3.5VB and see if that works. I found the DAC3.0VB to be much better than the CD2 in my system. Hope this helps and best of luck.
Final thought -- if you have a Bel Canto dealer nearby maybe try the CD1 feeding a DAC3.5VB and see if that works. I found the DAC3.0VB to be much better than the CD2 in my system. Hope this helps and best of luck.