In reply to:
Are there any speaker technologies that don't get damaged by loud square waves?
One thing you could do if you WERE looking to protect your speakers is find the Speaker Z (in ohms - 8 for most Axioms) and the Peak Power (or 4x Continuous Average Power is a good base) and cross reference them on a fuse nomograph, and put a slo-blo fuse in serial to protect them from thermal damage (or a fast-blo instrument fuse to protect tweeters from large transient voltages).
(ie: 8 ohm, 75W Peak = 1.5A)
If anyone's that interested, I can bring home and scan the nomograph.