Hooking up my phase linear model 2000 preamp, to my model 400 main amp.

I had these two units for years,hooked them up back in 2001,found they needed some work, had them repaired they have sat in the shipping box ever since. I did hook then up years ago but don't remember how I did it. Now I have them again, and want to get them going . And don't want to burn something up hooking them up wrong. Can someone give me some direction how to do this. Thanks DRW.