When I asked JDS that, I got this:
Thanks for the great feedback!
Some C5 users have reported burn in to take about 50-100 hours. We always recommend natural usage; no special procedures are necessary."
It sounds good now with a few hours of use. Hopefully it will slowly get even better. Soundstage is very different than the BH. A lot of what seemed to be "down" is now more "up." This is especially true of bass, which seems to float more, instead of being, seemingly, on the floor. Left/right separation (which has increased) is still on the sides, but the whole up/down/middle seems much more spacious than the BH.
As for your disk, try using a different disk, and also try doing a firmware reset (pin in hole). I'm running a 64 with no issues.