My friedn has the C352 and the C355 and he said for them to get to their best, they took a min of 50hours running time.
I auditioned them a month or so back with his M/A RS8's and my RS6's and they were both superb. Plenty of sweet and well timed bass, superb midrange and really nice smooth treble.
Just run them in and keep listening. The sound will get sweeter and sweeter everytime you listen to them.