Hi,
Bose has the LOW impedance option for the A20, but the entire mic-chord assy is different. also the low impedance version comes without blutooth.
we had no mission last week when I was at work, so I had no chance to use the A20 on the agusta grand in flight, but yesterday I did a quick flight with a 22 to review the last things before my JAA FI checkride , and I was impressed by the quality of the A20.... very quiet!