Questions about SUT's

Kevin Carter told me his step-up would benefit from about 100 hours of burn in. He recommended running the outputs of my CDP to the SUTs inputs. Worked fine for me.

There's an SUT burn-in method described somewhere on Arthur Salvatore's website. He reported good results.

I am sure they do, all components need some break in. I can not remember the name, but there is a gadget that steps down a CD player output, to run through a phono stage/SUT, with a CD player on repeat. Sounds like what you need, I am sure someone else can give you the name.

My MC SUT (Denon AU-S1) sounds better now that I have some hours on it. I also used the Cardas test album to help expidite the burn in process. I'm using different cables on mine but will get around to making them the same someday (the placebo effect).
I would not hook a tuner up to it.
Enjoy the music