@sychan Thanks for the tip. As mentioned in earlier post on this thread, I went with a HiFiBerry Amp100 to experiment with and see what system I want to use. The Amp 100 has very similar specs as the S.M.S.L. SA300 but with a bit more power. The software is an important part of all this. The HiFiBerry OS has a lot of features for parametric EQ, room correction, and other channel specific processing. It seems like a reasonable choice for building powered speakers with the Beocreate 4 amp or, in my case, assembling a second system with passives.
The OS continues to evolve and looks like it will have support for music storage soon if not already. It also supports Roon, Spotify Connect, blue tooth, DLNA, and airplay plus it has SPDIF input and output. I like that any room correction or EQ I set up will be applied to all inputs and not just what I set up in Roon.
If folks have built with Beocreate 4 then I'd be interested in hearing their experiences building software crossovers. I may do that in a future project.