Hey, I'll try anything once...

I've never hardwired headphones to an amp, but I have hardwired a CDP, integrated amp and speakers together with very good results. In my opinion, the best connector is no connector at all. I'm changing the cable on my Hifiman HE-500s to Jena Ultrawire anyway so I may as well try it!

Hmm... I thought that mil-spec cpc connectors were typically used in the auto, aerospace industries and the military for harness'... might be interesting.  

Nothing really... my preference is pure copper because to my ears it sounds smoother. I find brass has an "edgy  bite" in comparison.

Thanks for your suggestion Dsavitsk... can you point me in the direction where I can get a 4 pin XLR plug and socket that uses pure copper or high copper content contacts, like the  DH Labs or Furutech connectors? Thanks!

Is there any reason electrically why a single 3 pin XLR plug and socket can't be used instead of a regular single ended 1/4" headphone jack and socket? I'm aware that this isn't the conventional connector type for headphones and headphone amps, but I want to avoid using any brass or nickle...