Since almost a year, i'm using a sennheiser HMEC in the S76, i'm very pleased with it. The sound is briljant, the passive damping better then peltor, then you get the active reduction on top. The weight is comparable with the peltor. I've bought a pair of gel-seals, that finishes it. They (Sennheiser) had a trial made for a High-low impedance headset. I've asked for it, the send it over from the factory in Germany(through the dealer), it worked in the Dauphin (low), but it did not in the 76, The mike gain could not be opened far enough. So i bought one for the 76. Then, 1,5 month ago I also bought a HMDC (low impedance) for the EC155. It also works perfect!
http://www.sennheiser.com/sennheiser...ducts_aviation
http://www.sennheiser.co.uk/uk/icm.n...opter_headsets