I can tell you 4 reasons why I use the Bybee Ultimate Speaker Filters.
#1 - They work and sound great.
#2 - I don't have any crossover unit and there is nothing between my speaker driver leads and the Bybees except a pair of Cardas posts and 11 inches of Nordost SPM cable.
#3 - Anything that is inside the speaker cabinet is subject to far higher amounts of vibration than something outside the cabinet.
#4 - There is at least 8 times the filtering in the Ultra Filters than in a single Purifier. All Bybee users will tell you that more Bybee is better. I don't know if there is some kind of upper limit.
I can agree that when using 3 way systems such as Nrchy, it may be advantageous to place the purifiers after the crossover, at the drivers. However, he expressed trepidation about going into too much "surgery" inside the box. And the caveats above still apply about the vibration, and the smaller amout of filtering. I would add a warning about changing the stuffing of the cabinet, that it could change system Q and result in an unknown sonic difference, that may be better, or worse. If much internal surgery is now up for discussion, high quality caps, chokes, and wire in the crossover networks is in order as well as possibly wider spacing between chokes and other field-sensitive devices. Brass screws on the crossover mounting could also yield improvements, and even relocating the crossover to outside the box has been known to cause improvements due to lessening the vibration on the network. Damping driver baskets can help. Redesigning the crossover for bi-wiring or tri-wiring may help, if you know what you're doing. Even eliminating the crossover altogether, and using active electronic crossovers and tri-amping is an option. How far do you want to go?
