Does anybody make...

Your looking for an Active Crossover. What you're trying to do won't work. All the Macs have the outlets they are not separate. If you turn down one pair of outlets you turn them all down. First Watt make two active crossovers, one for OB and a 2 way.  One as a standard 3 way crossover.

STL makes an active tube 2-3 or 4 way crossover. 

In the 70s I ran a pair of C8s (I think) mono tube preamps. 

You can run more than one preamp.. I've ran a pair of C20 one for Bass and one for mids and highs..

Regards

I wonder what a Distribution amplifier sounds like. If you want to go inexpensive use a 2496 Behringer. I personally wouldn’t use it for anything other than bass management. It will however let you work out the kinks in a system a lot easier than anything else I know.. 300.00 or so. Cables and amps are required for every XO point. So Lows Mids and highs. I use a passive on mids and highs.. so it works perfect for me. The subs are servos.

I still used the active XO to worked out the model. It made it super easy to make the passive mids and highs XO.
Mine did incorporate LPads in leu of fixed resistors for DB matching..

I think I understand what you want to do? I think..