To @asvjerry trying again, the last shared photo link did not work. Deleted that post. Trying again, sometimes Google Photos is tricky and fails to present images on Agon. Some inspiration for your upgrade journey, its worth trying :). If you don’t see the photos, it did not work, lol. If you can see it, that’ is two separate crossovers for each speaker, one for the mid woofers and one for the AMT, separately. Won’t ever build these again, way too much work, last bucket list set. 

Speakers are bi-ampable this way too. Bottom line, these two Nomex 8s work way better than one 12" with a passive radiator. The two keep up with the Heil better and less need to suppress the Heil this way for better blending, matching. Picks up some efficiency too. Tube amps, Class-A solid state lower power amps, it all seems to work. First time I heard these with my big tube amps was a nice surprise. Best of Luck on yours.

*Loud fanfare*  Yay, pics! *L*

Would one object if I cut to the chase with some outboard X-overs I have?
I've an older dbx 2way, a more current Behringer 2496 w/sub out, and an ESS Eclipse 2241AM which seems to be a rare bird item....

On that latter one, any insights or comments on it would trigger high gratefulness from yours unruly.🤞🙄

Bi-amp is easy, multiple means of splitting off a sub...or not.  A/B entire, but I'm a First Watt believer even if no tubes involved...although I wouldn't cringe to own one.
But no rush on that, I can get as complex or simple as desired or needed.

8", huh?  Fav of the single driver crewe....  All forward, no back?  Curious, given the AMT dipole in cut-away slots...🤷‍♂️

@avsjerry I’ve an older dbx 2way, a more current Behringer 2496 w/sub out, and an ESS Eclipse 2241AM which seems to be a rare bird item....

Electronics Crossovers:

Why not test and try the 2241AM. I have one of those too :), but don’t use it right now. If I had two of the same amps I’d try it again. Maybe some bits to replace inside due to age. Might be a future retirement project redo. Try that if you can, and then compare to your Behringer, w/sub out. That might sound better if you have really good subs. That sounds like a good idea too. Go for it!

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Rear-V:

Re: AMT Di-pole rear "V" design is something I tracked to with another group of engineers when ESS Labs got bought out and was shipped overseas to Europe for a number of years. See ESS 450 below. Saw this in euro and us photos too.

ESS generations of the Co:

Later they went over brought it all back on containers/boats. I’ve got photos of Transar ATDs in rows that came back to LA stored, argh.

Future:

At one point I had this dream of waiting til they are done and buying ESS, what was left of it, and bringing it right back to Sacramento CA as my last bucket list retirement project. Good to have dreams. No need, I can build my own now :) I had a local audio chain ask me to manufacture/build them and they would sell them in their hi-fi room. I guess I wanted to keep my designs private, just for me LOL.

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Another photo for inspiration. :) ESS 450 not regularly seen here in the USA.

Hey they even had your vision for 7" drivers with AMT, here it is.

ESS Connoisseur Series AMT 450 Loudspeaker

Back to the OP, hahah, @sputz asked for some 3-ways. These are somewhat unobtanium. Transar ATDs.

Posting just for fun. How’s it work, don’t ask...LOL.

Bouncing flying-saucers for midrange. Big sub too.

Another I found on the net posted by some lucky bloke.