My system is sounding better and better. Since I've made so many changes over the past few weeks (cables and preamp), I'm not sure if it is these other components that are slowly breaking in, or if the NC500 really takes THAT LONG (several hundred hours now). I've still got a few cables that I want to replace in the next few weeks (I'm taking the DIY approach and making my own, so progress is a bit slow), and I have some more GIK panels on order, but I'm now quite pleased with the sound.
The power cables seem to have a bigger affect than I would have expected. I'm not spending a lot - using DH Labs Power Plus cable and a mix of connectors ranging from relatively inexpensive 'audiophile' connectors from Amazon to Furutech Fi-28, but keeping them as short as possible for my application (generally around 3ft). I haven't gone back to A/B the old cheapo power cables, but the bass is deeper and tighter, background is quieter, and overall, the sound is considerably smoother and more refined. Some of this could be the NCore amps (or Parasound preamp) continuing to break-in.