Do they even need to be waxed?
I know you will say yes, because that is the theme of this thread, so I will put my next post right here.
The preservation of something old is a noble goal, but are you preserving it or changing it? This is a tricky question. at some point changing it does preserve it better, but at some point it is change for the sake of change. They built new stuff for the sake of change, no need to bother with the old.
IMHO with a rare and expensive headphone this is VERY similar to repainting an antique motorcycle. The bike is often worth more with 1/4 of the original paint flaking off, and the rest shortly behind VS a full brand new paint job.
to add another question:
If the woodies need to be waxed, what condition do you think that they are in when none of the previous owners of these 5 (or so) year old headphones has ever done it? what about 10 and almost 20 year old woodies?
and as a third:
are you more likely to remove the lettering from a headphone letting it sit on your head and treating it well, or while buffing the new coats of wax?