As mentioned previously, SONY shipped the US version of MDR-EX1000 with RK-EX600, a regular oxygen-free-copper(OFC) cable of MDR-EX600, instead of RK-EX1000, a 99.99999% (7N) OFC cable in order to keep the price competitive in the US market. However, because of this, headphone enthusiasts began to report the audible differences of the two cables, and of course, it was most likely that the 7N was superior in sound quality.
Is that so? In order to verify the above claim, I purchased the RK-EX1000SP from Japan for ¥4,410. From Tokyo, it took about a week for the shipment to get here in California.
Compared to the MDR-EX1000's original 7N OFC cable, RK-EX600's built quality is quite flimsy. It's definitely thinner, and the plug is made of out plastic, instead of metal; definitely looks cheaper.
SONY MDR-EX1000 is to be measured with a regular OFC cable, a 7N-OFC cable, and finally a random non-OFC cable, while the physical placement of drivers are to be unscathed in order to eliminate such measurement deviations. Should any differences occur, they are to be reproduced back utilizing a binaural recording method to be ABX-compared.
RK-EX600: there is about 1 Ω difference, with RK-EX1000's being lower, due to the fact that it is 7N & thicker in diameter.
ATTENTION: In order to accurately reproduce these binaural recordings, listeners must use a flat diffuse-field equalized headphone, such as Etymotic Research ER-4B and STAX Lambda PRO with ED-1. The accuracy of the reproduced result can not be guaranteed otherwise.
It is evident that the 7N-OFC cable's electric conductivity is superior compared to the regular OFC cable. Yet, let us not forget: MDR-EX1000's impedance is 32 Ω, which is quite high enough to withstand the damping effect of most of the portable sources' output impedance: Practically, the effect of 1 Ω difference would be infinitesimal. If this difference should be discerned by the ABX-comparison, the one must have a hell of hearing ability, or have what-so-called a golden-ear.