Bill,
The Low B-2s are both the full range models, and they are terrific.
The question of stereo or mono is not all that simple. In general, I would not even consider amplifying an electric bass in stereo (each pickup independently). My circumstances that lead me to go full stereo are somewhat differrent, but more about that later.
Having said that, with an S2 you've got the best electric bass known to mankind. With an instrument of such sophistication and so much attention to fine detail, you may want to give it the best amplification you can. There may be benefits to a full stereo system, but they would probably be marginal.
Even with an S2, I would still likely to stay with the F-1X. The F-1X is a fantastic piece of gear, arguably the best there is out there.
A stereo power amp, however, still makes sense. You can use it in bridged mode to have lots of power, or use the cross over on the F-1X and bi-amp your instrument, or use a stereo chorus pedal after the preamp and take advantage of the two channel system that way.
With two full range Low B-2s there is no real need to amplify the lows and highs separately. You can take just one for a small gig, or take both to a larger one. If you ever need to be even louder, just hook up to the PA from the F-1X's balanced output.
So don't get rid of your F-1X just yet. And in any case, if you do want to go full stereo, you can always add a second F-1X later. I would have done that too, but I had no more room in my four space rack sleeve, and did not want to get a bigger one.
I decided to go two channel because all my kids play music, and very often there are two instruments being amplified simultaneously through my gear. One may be a double bass, while the other one an electirc bass or a keyboard. This way I can easily separate them, and being full range, my Nord Electro's B-3 simulator also sounds great. And to top it off, it is also a very handy and high quality PA system, terrific for parties. At present we have no full time musician in the family, and I am really happy to have such multi-purpose gear in the inventory.
Mind you, the primary purpose of the equipment is still bass amplification for my daughter to play her short scale S1 or her Jazz Bass, and I am more than happy with the sound she gets.
This is my point of view. Yours is probably different. To start with, try your S2 with your F-1X driving a stereo power amp and a pair of full range Low B-2s. You won't be disappointed.
You can evolve your system from there as your needs change.
Have fun doing so,
Peter
