Someone w Experience Active/Passive Biamping

As any Linn person will tell you, active multi-amping is the way to go. However, this presumes that the speaker is designed to be upgraded in this fashion. Many speakers are designed as a total package, drivers are matched to the crossover as it is presently implemented. If you start messing around with the crossover, the speaker may behave in a way that the designer hadn't anticipated. Unless you've asked the manufacturer whether the speaker can be used with an active crossover, it's a leap of faith whether it will improve its performance. I would have regard to Eldartford's comments.

I'd go with an active line level crossover.
Apart from a higher damping factor and increased efficiency it gets rid of the horrible effects that come with having inductors and caps in the audio path!
Inductors introduce phase shifts and eat power
and caps smear the signal.
Passive components are best avoided, they are always detrimental to the signal apart from straight wire of sufficient thickness.

I just called Magnepan and asked about bi-amping the 1.6's and the 3.6s because I have exactly the same thing in mind. I was disappointed.
1) According to Magnepan, the 1.6's CANNOT be bi-amped, and they should NOT be bi-amped because it will do strange unintended things. The two sets of inputs actually go to the same place, and that in fact on the 1.6's the two inputs are mainly cosmetic for people who want to bi-wire and think they are getting some benefit from it, when really it does nothing because of the way the 1.6's are set up inside. Sorry about that. I was hoping to get 1.6's for myself and bi-amp them. :(
2) However, the 3.6's can be bi-amped no problem - they are a different animal.
Lesson learned: call the experts and ask first.