Hi Damien
Sounds like you are taking a similar path to mine - the difference being that you are using minidsp to do the crossovers whilst I'm using Roon to do that. And you have built REW profiles.
But I'm confused. You say you are very impressed with the results so far but you still need to sort out the amplification. What amps are you using so far and why is that not good enough?
In my experiments I've used a multi-channel Sony AV amp and whilst not state of art gives very acceptable results.
Current: [P20] Roon/Tidal > Custom PC> Chevron Paradox NDF16 > Phast Pre > Neuro. 686 > Tannoy Berkley (RFC tweaks)