List of most high end analog active crossovers ever made.

I use the low pass section of the Dahlquist crossover, which uses active devices to provide an adjustable 18db per octave slope.  Mated with the active internal high pass filter on my Beveridge 2SW amplifier/speakers, the crossover point is "seamless".  As a general rule, most of the tube based crossovers, Marchand excepted, provide only a 6db per octave slope, like the ARC one.  Solid state crossovers are more likely to provide higher order slopes (12, 18, and/or 24 db per octave), typically. (There are exceptions to every rule.)