Hey Mr. Geezer and all concerning headsets,
I'm flying w/737 for almost 4 years and I've bought a new headset and took my 1 month to decide what to buy. So I can help you all guys who are planning to buy a professional headset.
First of all, need to decide what kind of headset to buy. I highly recommend ANR (active-noise reduction) headset. And these are all around 1000 USD.
And the very popular and mostly used one is definetly BOSE A20. I was gonna buy that one but after a long investigation, I ve ended up with AKG AV100. And other than these, I read about Sannheiser and Lightspeed.
To tell you guys briefly the difference; BOSE A20 is a good one but if you are flying long flights as well and want to listen music quietly with iPad on flight deck, with A20, it's really hard because A20 offers you only Cable connected bluetooth connection which sucks. You pay 1000 USd and you can not connect your iPad/iphone (whatever) and listen your music on long-boring flights. And ANR function, believe me within 4 big-brand headsets, there are slight differences that you can not understand the difference. All headsets use almost same technology and so no difference.
Other issue; AKG is new in aviation but it's Harman sub-brand, so it's like Bose, a sound system brand and between 4 of the big ones, the most comfortable is AKG.
Well, I can write a lot here but instead of that, if you guys any specific questions about headsets, write here and I ll reply.
Conclusion; do not buy any without taking a look at AKG-AV100