Playing with all full range drivers, there had been no crossovers for me. Every time, even a single component in between the signal path from amp to driver, started robbing the midrange magic, where so much thought I give to the choice of amps, tubes for the magical midrange, so nothing should come in between, was my experience.
Adding a phase plug is very interesting thing to do just to widen the HF dispersion. The 12” FRD I have, has s very narrow HF dispersion so I may attempt one. 8” Alnico is great overall may be because it has a phase plug already.
I am yet to learn miniDSP tricks and it will be to tame and amplify the bass only.
All above for OB setup only....