I'm using a little HiFiBerry AMP+ that's mounted on top of a Raspberry Pi 3 Model B in our family room to drive some old JBL 4311B studio monitors. The RPi is running Roon Bridge, so it serves as a Roon output. This combination sounds surprisingly good. I have not tried this little gizmo in the big rig, but it's clear that there's fun to be had at all price points in Class D these days.
https://www.dsnyder.ws-e.com/photos/potn/HiFiBerry_AMP+.jpg
https://www.dsnyder.ws-e.com/photos/potn/HiFiBerry_AMP+.jpg