During the last days the CD8 has become somewhat bright, sibilants seem enhanced. I hope that after burn in the tonal balance becomes fuller again!
This is the same rollercoster I expirienced whan I was breaking in my old CD-7. The sound was changing from dull to bright and vice versa.
This is why I resisted the temptation to listen the the player fresh out of the box. Based on your expirience with CD-8, I may even extend the initial burn in from 10 days, to full 20 days. It will give me more time to play with the dCS Puccini I still have on loan.