Asking first before buying would take the fun out of it
They were going so cheap I just jumped on them. I did have an idea that if I weren't happy with them they can become my passengers set hopefully when I've got my PPL.
I've tried on a set of 13.4s and they seemed comfortable but I've only used the peltor 8006 which I can only assume is pretty much on par.
Your right though 13.4s would be a safe bet because they're specific for civi aircraft. I guess my main worry is the microphone the 10-76 has a dynamic mic which possibly won't work on the dr400, I've got the adaptor for the u-174 lead but also whether the mechanics are better.
Headsets seem to be a very grey area, it's a pity you can't try before you buy
