Hi Hans -
Nice speakers! What is it that you're trying to achieve or optimize with these speakers? As has been already been suggested, "upgrading" the crossover is likely not the place to start unless you've tried everything else.
1) Be sure your speakers are placed in the room per the manufacturer's recommendations. The RF-7II speakers aren't terribly fussy about room placement, but they do need a bit of room from the rear and side walls to sound their best. Somewhere between 12 - 18 inches from the rear and side walls should work. Try a bit of "toe - in" with the speakers, with the horn aimed either at or just behind your ears at your listing position. Your actual experience may vary, but it is typically suggested to position your speakers on the "long wall" of a rectangular listening room rather then the short wall.
2) Once placed and aimed correctly, if you're still not hearing what you want, the next logical place to attack is the listening room: acoustic treatment. The acoustics of the listening room itself is often THE weak link on the path to audio bliss. Think about it: you can put the most expensive and objectively wonderful-sounding speaker ever made in acoustically-challenged listening space, and that speaker will sound like crap. What you do to optimize your listening room is very dependent on the room itself. Consult sources on the internet for inexpensive tweaks to get the most from your listening room.
