you can try and contact ASUS direct
I did, they were as helpfull as a chocolate watch in a sauna.
Asus stated no spares were carried for that headset, and that the earpieces were not covered by any warranty.
Which is a shame as I have a perfectly woking Asus Vulcan ANC headset I cannot use due to no replacement bloody pads.
Hell even OCUK could not help, I had bought the Asus Headset from OCUK December 2012 for occasional gaming, and by June 2014 it's earpads pleather had just crumbled around my ears.
I ended up buying the HyperX Cloud headset from OCUK as no where could I find an answer, as many Asus Vulcan owners who have had this issue could attest.
I was not bloody happy having to spend another load of cash on a headset. I bought the Asus based on reviews, it replaced a barely used razer carcharias that stopped working due to a wiring fault.
As least the HyperX headset comes with spare pads. 3rd time lucky. But I would still like a set of bloody earpads for the damn Asus headset.
If OCUK could find suitable replacements I am sure their would be a customer base buying them, as a quick google will show this is a common problem Asus have known about for years yet seemingly ignored.