Choice of headset is a bit like which car do you like, a very much personal thing. We have both Bose and the DC ANR sets and whilst I prefer the Bose there are good and bad points for each type.
As for 76's, they come as a low impedance mic audio system and let me say, our new C+ have the standard audio boxes fitted and they have the worst speech circuitry I have ever heard on an aircraft. The setup of audio levels between receive audio, sidetone and ICS will make or break a audio system so the greenies (English term for avionics guru guy, comes from their Navy I think) need to get that right to make it work.
DC ANR - a little too heavy for me after a long day in the seat. I have used a number of different models including the lighter weight H10s that broke attaching parts and the like. The current 'hard' plastic type is more robust. The DC does have better passive noise attenuation than the Bose by its ear cup design and clamp force.
The Bose is very comfortable to wear I find. The later version has a much better battery/controller design than the previous model however, the volume control knobs that are mounted on both sides are easily knocked. This I fixed with an elastic garter consisting of some dressmaking elastic about an inch wide stitched in a circle of a suitable diameter to slip over the controller and over the volume knobs. Works a treat.
ANR as against non ANR - for me never again. Noise is a significant fatigue factor and whilst the expense of ANR to passive is not insignificant, your hearing will deteriorate with repeated exposure to noise over time. And anything that reduces that exposure is a good think me thinks. The comprehension of radio traffic is also greatly enhanced, particularly if you have to fly in an airspace system like that in Nigeria.
Low versus Hi impedance – The disadvantage of the Bose is that you either have to order the low or the hi Z mic assembly. The mic assembly includes the controller that also houses the batteries on the non-aircraft powered models. To have both hi and low Z systems covered therefore can be at a cost. However, if you purchase a lo Z mic assemble, there are after market adapters, some box types like the Carter, or inline types which will convert your lo to a high when plugged into a hi Z system. These adapters use the mic volts in the aircraft’s mic circuit to power a little amplifier. If you purchase a hi Z mic assembly, you still can by an adapter for Hi to lo but it will require its own power source (a battery) to operate, all a bit messy. The DC doesn’t have this problem as it has a hi/lo switch.
Cost – Both makes more expensive, Bose more expensive than the DC. My experience with the after sales service of both companies is excellent. One of our guys had a problem with his new DC, it was replaced immediately without fuss. Similarly, my newer Bose had a problem, was replaced immediately.
My view, ANR is a worthy investment and very much a personal choice of type. If you can, borrow one of each type to try before you buy.
Geoff