I think if you are purchasing only the headphones you should be okay. I have a pair of 400 series that are almost 20 yrs old. The issue is getting a Stax amplifier from Japan. If audiophilia nervosa permits the use of a 120v to 100v step down on your amp then it would be okay too.
i would probably go to an off brand amplifier/e/nergizer. there a modest saving on a new pair on ebay. I find true bargains to be rare. Everybody is smart. I am just not sure it's worth the hassle. You pay for what you get.