I initially tried the RED Phones solution and it was 'ok' but not brilliant. And the ear pads were less comfy because they were full of plastic instead of padding.
Pretty quickly gave up and switched to earbuds which are waaay better sound (Shure SE535
). They sit ready flush with the ear so they're comfy all day even under a helmet. But I don't like that they block ambient sound so efficiently.
So still looking for the idea solution. Be a lot easier with just a beanie!