Solution!
Howard Leight R-01526 Impact Sport Electronic Earmuff: Amazon.ca: Tools & Home Improvement
+
http://www.northtrailsports.com/TWO-...duct_info.html
+ generic 3.5mm-3.5mm dual male plug
=
"Real steel" comms headset with heading/ear protection!
I've owned a set of these and the sound quality of them is actually nicer than my real steel MSA Sordins, IMO.