Here's my take:
1. If you can use the Barbetta as a pre-amp for the CM-30 that might boost its output.
2. Since both amps would be running the same signal (not 2-way, no split) the Sona could very well overpower the CM-30.
3. I doubt the CM-30 would blow up. You could experience distortion.
4. Use the CM-30 as stage one and send its signal to the Sona.
5. Use the set-up where you would normally use just the Barbetta and then add the CM-30 and play with the adjustment.
6. If you can use the 31 as a sub only, the separation and disparity of power should not make much difference.

ABOVE ALL, the CM-30 is for small areas, so use it where it alone would work and then add the Sona 31 for bottom end. Good luck.