First off, after reading the 9 page thread on the electronic muffs, it appears that for my purposes, these would be the best option.  

Where is everyone getting theirs?  It looks like Grant had them at one time possibly, but they aren't on his website.  (Though if I email him I know he'll be as helpful as always.)

Secondly, I'm trying to find out which adaptor cord, if any will work with my radio system.  We use Comnet Ericsson radios (aka Jaguar).  I'm not seeing anything initially that looks compatible.  Suggestions?