This is for those who want an inexpensive replacement cable for Hifiman headphones, and can't make their own cable.
 
The stock silver cable that comes with Hifiman headphones tends to be very unruly. I've tried smoothing out the kinks, but the cable seems to have some sort of immortal memory of how it came in the box. And the microphonics were bad enough that I couldn't even use them sitting in front of my computer, as they made loud grinding noises when the cable slid around the desk. Searching for a shorter and more flexible replacement cable, I was dismayed to see that all cables are long and expensive, as well as commonly made of silver. I think the stock cable can be had for $60-$70, whereas most aftermarket cables are well into several hundreds of dollars. Hifiman thankfully does sell the connectors in pairs, which is probably a godsend to those who make their own cables. Points to them for selling the connectors for only $10.
 
But, not everyone has the skills and equipment necessary to build a cable. There's a solution.
 
Thanks goes to Steve Eddy for correctly identifying the connectors as SMC. Saved me the mistake of purchasing SMA connectors, which look similar, but are larger. Also agree with his comment, Hifiman probably could have picked a different connector.
 
SMC connectors are usually used for high speed data transmission in the GHz range. It's pretty uncommon, but there exist SMC to BNC adapters. You'll be looking for an SMC female to BNC cable. Search on ebay for "SMC BNC" and look for a short cable with SMC female on one end, and BNC on the other. There exist adapters that are SMC to BNC, but they are very expensive, and add so much length to the bottom of the headphone, that you won't be able to turn your head. I chose to go with a BNC male, as the BNC female includes a plate and threads for mounting in a panel, which adds bulk. Don't forget to order two. The SMC cable I purchased has a larger nut than the stock Hifiman connectors, but the headphones have a large enough recess to accommodate.
 
http://www.ebay.com/itm/Cable-BNC-male-plug-to-SMC-female-jack-straight-RG316-Jumper-pigtail
 
Next, you'll need a pair of BNC to RCA adapter plugs. They exist in all gender combinations. BNC male to RCA female and BNC female to RCA male are highly common, BNC female to RCA female not so much. A search on Amazon for "BNC RCA" will list most of them for you. I went with Gino BNC female to RCA female adapters.
 
http://www.amazon.com/Gino-Female-Coaxial-Adapter-Connector/dp/B0076UHKVY
 
The last part will be the RCA cable. There's plenty of TRS to RCA cables to be had, so you can pick whatever you like. I went with a Monoprice cable.
 
http://www.amazon.com/Monoprice-Designed-Mobile-Plated-Stereo/dp/B00AJHBES6/
 
SMC to BNC cable 2 x $4 + $1.50
BNC to RCA adapter 2 x $4
RCA to 3.5mm cable $5
 
$23
 
And that's the cheapest cable I could get for Hifiman headphones. The adapter stack is somewhat large, which may be a bit of a bother if you have a substantial chest. The microphonics below the adapter stack is dependent on what RCA cable you purchase. The cable is microphonic from the adapter stack and above, though that probably shouldn't be a problem except with certain collar buttons or zippers. The SMC to BNC pigtail is flexible enough that I can still turn my head 90 degrees to the left or right, though you can easily feel the weight of the adapter stack on your upper chest.
 




 
http://imgur.com/a/F48eV
 
Oh, apologies to anyone vomiting at the sight of HE-500's connected to a $5 Monoprice cable.

.

Oh, that's pretty inexpensive for cables made on order. You could order pig tails to be made from them SMC female to 3.5mm mono female, and then use 3.5mm stereo to 3.5mm mono cables, the kind that the Brainwavz HM5 and NVX XPT100's use. RHA sells a cable that's braided.
 
http://www.amazon.com/RHA-Fabric-Braided-Headphone-Cable/dp/B007L1L9CO
 
The prices on those stock Hifiman cables are much more reasonable on that site.
 
That last cable though, 1.5M length and $25? That looks like something I'd like to buy, but the site's all in Chinese

I just came across this thread. How's the quality of this setup? I just got my HE-500s, and I see a lot of people spending $250 or more on cables. I'm interested to hear about how this sounds.

I can't detect a difference in sound on either my HE-300 or HE-500. But, my ears aren't golden, in fact, they're made out of rusty zinc.
 
Most people who frequent these forums are not the kind of people who would attach cheap cables onto such an expensive pair of headphones, so you're unlikely to get an opinion of sound quality without trying it out yourself. This is really for people who are seriously bothered by the stock cable, or who just like to experiment.

Just got my 400's in. Will definitely favorite this page and try it. 

seeteeyou said:

This one is only 150 RMB or 25 bucks

http://item.taobao.com/item.htm?id=23233512573

Click to expand...

I wish I could buy this but it seems I cannot sign up. Maybe only can buy in China

Yes, that's the one I was interested in. Taobao does sell internationally, but not as easily as it could be. To quote an excerpt from their website:
 

If I didn’t want to use an agent, could I order direct from Taobao?

Wanna go rogue, eh? We admire your spirit! But unfortanetly, you won’t be able to add any money to your Taobao account. Taobao’s Alipay (like Paypal) can only be funded by Chinese banks, or by buying recharge slips locally in China.
 
 
So it appears that buying from that website is going to be very involved for foreigners.

I just bought some silver plated oxygen free copper wire and hifiman connectors and rhodium 1/8 plug to make my own wire from this place..

http://www.plussoundaudio.com/diy/wires.html

Thank you so much! 
 
Bought a pair of second-hand HE500s, and the cable conked. And I stay far away in India, where all this audio-equipment isn't exactly easy to access. Followed your guide to the T, and managed to fix it. Opeth is blaring out from them babies again, and I have you to thank for it. Thank you, thank you, thank you!