I tried to research this question a couple of years ago, and really never got a certain answer. I do remember though that the impedance was listed as being exactly the same (56 ohms iirc) so I assumed that they were the same internally. If not that would be quite the coincidence. I had mine reshelled about 1.5 years ago, and still love 'em. Good luck.
5/23/16 at 6:37pm