You can mix it up, as you state it. Use the 2500 for 'bass' and the premier on the high end. I bi-amp a c-j premier 11 tube amp along with a c-j mf2250 into my kef ref. 3-2 speakers. I have two sets of connectors at the back of the speakers to run seperate cables to. Be sure to remove the 'jumper bar' connecting the two together, if your b&w's have a similar set up. Remember, one set of cables from the premier to the high end, one set of cables from the mf to the low end. This is true bi-amping. Also, you will need two sets of cables connecting from your pre-amp to each amp, or may require a spliter jack.
Regards,
Regards,