Questions about biamping

I recently sold my speakers from my second system and was thinking about biamping my main system. I have a CJ 16LS S2 preamp and a Jeff Rowland Model 10 amplifier. I am thinking about using the Model 10 for the bottom and my Sonic Frontiers SFM 160 monoblocks from my second system for the top. The Model 10 is 150 watts and the Sonic Frontiers is 160 watts. Do I need a crossover or can I just hook up both amps to the preamp? Would the difference in watts make a difference? Thanks for any help.