Can someone explain to me what it is exactly (and if you could put it in laymen's terms, that would be grand),
and which phones have it,
and how is it done?
I have both an ED-1 and an ED-1 Signature.
I believe (though I will go about checking) that, as well as the equalisation of frequency response for diffuse field, there is some degree of cross feed of left to right and of right to left.
I can find this out easily enough when once I get these two machines out of storage....
You may already have seen this, but there's an explanation on the North American beyerdynamic website:
You'll have to fish a bit, as it's one of those expanding section affairs.