I'm not sure about the F-2B, but our local guitar guru Bill tgo said in another thread that he asked the good folks at Alembic and the F-1X also uses the pre-amp of the classic Fender Dual Showman as its blueprint. Some say the F-2B is better suited for guitar, I wouldn't know. I don't own one, so I have nothing to compare it to.
Also please note that I bought the F-1X for my Persuader's rig. It was my good fortune that it works for me for guitar as well.
The differences (I think) are not so much in the pre amp section as in the other features of each. The F-1X is a one channel preamp with DI's, effect loop, and either crossed over or not. The F-2B has two channels. As far as the other differences, I'm not real sure. I do know that they are different animals, and they list for the same $$'s. Someone better versed may climb aboard soon to better explain......
(Message edited by hollis on January 07, 2005)