http://www.gulf-coast-avionics.com/detail.asp?id=4446

Paul kgyy wrote:

Does anyone know of an adaptor that would allow, say, Ipod input to the
headphones? Ideally, it would have internal electronics that would
ramp the audio down when ATC transmits.

I know that many ANR headsets have this built in, but I have a passive
set that I like well enough to continue to use.