Hi Curt
I have a medium size room 17'X17' and monoblocks which are 250 watts per channel into 8 ohms. Is that too much power for these speakers? Can you explain which speakers in your system has an active XO?
_________________
Your room size is medium and should work well with 1SCs and a sub.
The MB-100s play at about 150+W (music peaks <= 10ms) and achieve full 1SC volume. Your 250W amps add less than 3dB to the MB-100s volume so you are in the right ballpark but you may only need to trun the Purist to 2 O'clock to get the same volume I get at at 5 O'clock. Still excellent room control.
The active crossover works best between the preamp and the amps. I'm saying drive the 1SCs with 70 Hz (or so) on up and the subs from 70Hz on down.
If your sub is active turn its filter all the way up and forget it, the line level AXO takes care of everything. Just use the subs volume control to balance the subs bass output with the 1SCs output level.