List of most high end analog active crossovers ever made.

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:

Wilson Audio have a couple, suitable for lower frequencies.

Wilson Audio - ActivXO and Watch Controller Active Sub-woofer Crossovers