Why HiFi manufacturers don't make active crossovers anymore?

Sorry, but my doubt is not considering a active crossover situation... I forgot to tell that the application that I described, is considering speakers with passive crossovers...

Anyway, I think I already found the answer, the M-73 is not a 4 channel amp, it’s a stereo amp, I was thinking that was a 4 channel amp because of the looks of the amps boards inside, it was appearing for me 4 independent amp blocks, and was thinking that each of the 4 speaker’s terminals was connected into each block...

So in fact, if use the M-73 to amplify 4 speaker’s drivers (left and right horns and tweeters), it can be done, just connect each driver to the respective speaker’s terminals, and activate on front panel A + B speakers together, but it will be bi-wiring, not bi-amping.

While the First Watt B4 I mentioned on Page 1 doesn't have all the controls and versatility of the Pass x/o, it has a lot more than the Bryston and Marchand. 1st/2nd/3rd/4th-order filters in 25Hz increments from 25Hz to 3200Hz. All discrete---no opamps or ic's. Level control on either the high- or low-pass filter (user-selectable), for balance matching between two amps with differing gain structures. Nice little piece at an affordable price ($1500 retail when in production, though discounted at Reno Hi-Fi). 

even Marantz offered a active crossover in the early 80's... amazing: 
http://www.thevintageknob.org/marantz-Ad-6.html

wish the mass HiFi brands return to produce such amazing lineup of products, how Pioneer, Sony, Marantz, JVC, Denon, made it.. 

Unfortunately that's not gonna happen hehehe

To make modern active one must use DSP and chips no small manufacturers can make chips so they must rely on what's available so basically you have a few versions of basically the same thing and its why smaller companies are avoiding for now. Passive actives are kind of like a model T Ford today still they have a subjective performance advantage if done right over DSP. DSP's great strength is making the wrong work correction is what DSP is mostly about for if the design was proper most of DSP uses are nulled. 

Similar to member chosenplay earlier in this thread, I am also using DEQX & Open Baffle speakers ’though in my case two processors. (HDP-5 - 3-way OBs as master & HDP-3 slave with two subs).

I am 62 y old, a vinyl listener since mid 70s & was extremely cynical about using DSP with an analogue source until I actually heard it in someone else’s system!

I then researched & auditioned/trialled numerous variations including Dirac, Mini DSP, Behringer, Acourate, even Linn Exakt in recent years but for me. DEQX provides by far the most satisfying results in spite of high cost.

The first time I set a correctly time and phase aligned crossover with corrected, time coherent speakers I literally swore out loud at the clarity, transparency, cleanness and sheer musicality of what I was listening to (this was with Shaninian Obelisks & a M&K sub that I had owned for years and knew the sound profile inside-out).

The phrase ’game changer didn’t come remotely close! (that was seven years ago & I progressed a long way since then with a setup that since early 2017 is as near ’perfect’ as I could want).

Any shortcomings that may (or must?) be present in terms of transparency are buried so deep in what I hear that the positives about absolute time/phase coherence (at EVERY frequency in the case of DEQX) completely overrule the negatives I never really appreciated in most purely passive setups that I had owned or listened to.

Any sceptics reading this - please keep an open mind before passing judgement until you hear a properly configured DSP setup