Basic Question fAbout a Preamp for Monoblock Amps

I am going to show my ignorance with this one.

I am close to buying a set of Adcom gfa 565 monoblocks to power my Maggie 1.7's. I am thinking to pair the monoblocks with a tubed preamp.

My question is about what kind of output terminals do I need on the back of the preamp? I suppose that I want two outputs with left and right terminal for each, correct?

What else is important to look for?

My second choice is an Adcom GFP 750.

Now you can provide me with your opinions!

Thanks,

Dsper