I run my SF-2 through the effects loop in my F1-X. If you are only running the F1-X as your sole preamp, you probably would look to run the SF-2 in mono mode. I run two amps so I run my SF-2 in stereo mode, with the A channel running through the effects loop of the F1-X and the B channel into the effects loop of a Fender Princeton Recording Amp.
Have Fun,
Bones