Research the Dahlquist DQ-LP1. Passive high-pass/active low pass. Very transparent with a polystyrene in the high-pass. Easy to upgrade, and still being used/supported in the high-end market. (http://www.regnar.com/Dahlquist_Speaker_Parts_Service_Page_DQ-MX1.htm) See page 13: (http://www.avahifi.com/root/audio_basics/ab_pdf/ab1989.pdf) Notice on page one of this review, what is used to bi-amp the system. (http://www.nolaspeakers.com/reviews/tas/exoticaGR_part1.pdf)
external x-over for sub....
Anybody make an affordable external crossover with variable settings and slopes? thanks....