Hi Koestner, I would second what Minorl said. I am running a Marchand active crossover and bi-amping with a valve amp on top and a SS Class A/B amp on the bottom. The advantage of doing this is that the valve amp does not "see" any bass frequencies, so its apparent power is higher.
The downside of using an active crossover is that the slope of the crossover will sum with the internal passive crossover of your speaker, resulting in a steeper slope and possibly introducing phase issues. Ultimately the best solution is to go fully active - bypass your speaker's internal crossover and connect the amp directly to the drivers with an external active crossover in place.
You can do this upgrade in stages (which is what I did). Start off by bi-amping, then add the active crossover later.
The downside of using an active crossover is that the slope of the crossover will sum with the internal passive crossover of your speaker, resulting in a steeper slope and possibly introducing phase issues. Ultimately the best solution is to go fully active - bypass your speaker's internal crossover and connect the amp directly to the drivers with an external active crossover in place.
You can do this upgrade in stages (which is what I did). Start off by bi-amping, then add the active crossover later.