List of most high end analog active crossovers ever made.

Lew, I think Roger Modjeski (who designed the electronics for Beveridge) has an updated/improved x/o for the 2SW, as well as a new dedicated direct-drive tube amp for the speaker.

I had the Dahlquitst DQ-LP1 for years, selling it only after I got a First Watt B4. The B4 is unbelievably versatile: high-pass and low-pass 1st/2nd/3rd/4th-order filters in 25Hz increments from 25Hz to 6375Hz. All discrete (Toshiba Jfets), no opamps or IC’s. Unfortunately, the B4 is no longer available assembled, only as a DIY kit. Nelson’s Pass x/o is even better, but sells for a lot more (the B4 listed for $1500).

I used Threshold 1x and 10x crossovers with Focal Bass Drivers (2-10" Polyglass Drivers: Polyglass technology, exclusive to Focal, consists in applying molten glass microballs on a cellulose pulp cone), with Accuton midranges and tweeters. Pass designed Adcom GFA 535 II, GFA 545 II and GRA 555 II were the amplifiers. I was still using a well broken in Pioneer C-21 (look at the PCB board and the thick traces of very high quality as well as some of the best components one could buy but it took a very long 500hr + breaking time otherwise it was far too bright).

If you want to see the difference between most of the garbage today and true engineering prowess view www.thevintageknob.org/pioneer-C-21.html 

Marchand makes a bunch:

https://www.marchandelec.com/electronic-crossovers.html

The SPL crossover has some nice features: