I use 2 basses (a 5-string Orion & a custom 4-string) and I would like to be able to switch basses mid-set while leaving the preamp settings intact to minimize time during the exchange. My plan is to use 1 power amp/speaker setup with 2 separate preamps with an A/B box switching the preamps to the power amp/speakers. My question is; Can I use one F2-B (1 channel for each bass) or do I need two F1-X's (1 preamp for each bass)?

The F2B will do fine in your application as it has a mono ouput which combines the two channels (as well as separate outputs for each channel).
 
The F2B gives you two separate preamp channels - the F1X gives you the deep switch, direct out and crossover.

BTW - welcome to the club.

Welcome to the club again, John
 
Friendly and helpful folks abound in here, and the only toll is...
listening to a bunch of Pauls banging beer bottles and shouting pictures, Pictures, PICTURES. :^)
 
I'm sure you'll find/make friends in this group.
Mike

So which preamp, F1X or F2B, can be used for an overdriven (SVT) style sound? I remember reading something about that here, but can't find the thread. I imagine it was by tying one channel of the F2B into the other.  
 
EffClef

Not exactly an anwser to the last question, but I think it is important to consider the direct out connector which is only available on the f-1x only. If it is your goal to mix 2 basses on stage, your amplification towards the pa system might be different if you use the f2b.
 
Cheers
Jan