How to break in a tube preamp?

Thank you everyone for your input. Much appreciated.
I am looking forward to hearing the post burn in period. By all accounts the teflon caps are wonderful once they have considerable time on the clock.

OH thats a tough one!!

I own a linestage with teflon caps, but i would never say that they are universally good--it is all a matter of voicing. A cap that works well in one design, and to one person's taste can be really bad sounding in another application. I've heard gear "upgraded' with Blackgates and teflon caps that sounded really bad. I know of people that search for fifty year old caps that sound great in certain designs (another linestage I own uses these kinds of caps).

There really isn't such a thing as good caps and bad caps, it is more the case of finding the right cap.

Based on my experience, my recipe for the best:

You don't need the amp on but you want a source playing music going thru the pre. I also believe in cycling the pre (during this time), ie, on all morning/off for a few hours/on late afternoon-evening/off all night til the next morning.

Two of my CJ preamps have teflon caps (ART 3 and ACT 2.2). I liked them out of the box, really liked them after a few hundred hrs, loved them around 6 months (have no idea the hrs at this point), and have been "in love" with them from a year on. They just seem to get better with time.

Enjoy the trip.