My fist MC. Softer sounding (not as loud at same volume setting as my MM)
Hate to ask, but, you did change the switch from MM to MC on your phono stage to increase the gain to match the lower output of the MC cartridge?
And yes, I believe all cartridges benefit from 50-100 hours of break-in. Should improve gradually over time until you get some hours on it.
I haven't had an MC cartridge in a long time. The phono section in my current integrated amp only supports MM cartridges.