I do not know when they changed the plug. Here are a couple of pics of mine. I have had them about 6 months. Got them full price on Amazon.com.
Right
Left
Right
Left
The only difference is the cable and the plug.
They come in several different variants:
HD 25-1 II
HD 25 II - same as HD 25-1 II, but with 2 m steel cable, straight jack plug
HD 25-C II - same as 25-1 II, but with 3m coiled cable, straight jack plug
HD 25-13 II - same as 25-1 II, but with 600 ohm impedance, 3 m steel cable, straight jack plug
BTW, has any of the HD25-1 owners here tried these headphones with the Amperior microfibre pads? Really like the feel of those when I demoed the Amperior and would consider purchasing it, but I was wondering what the change in sound and isolation levels would be (I typically use stock vinyl pads).
Okay, so I got the HD600 cable connected to my HD25 II's and the
attack is slow and sound veiled compared to the HD25 II stock steel cable.
Will it change after some burn in? Sorry if this question has already been
asked, but I couldn't find the answer.