McIntosh C-2200 Burn in time?

Just hooked up my new preamp. Have never owned a tube preamp. How long does it take for the Mac to start sounding it's best? Right now sounds a bit brite and the mids are thin and foward.

Also, has anyone noticed their Mac C-2200 picking up noise in the system? Have a lot coming through the speakers. Have a Mac MC-207 amp and Hyperion HPS-938 speakers. I know there is a bunch of Mac guys out there hoping I'm not the first one to have this problem!

Thanks