Here is the results that we find:
First of all, is there a difference between the stock Sennheiser cables to the aftermarket ones? Yes. This is the easiest part to detect during our cable review. The HD25-1 stock cable is a very bad quality one, the HD650 cable is better, but any aftermarket cable we tried simply betters both of them by quite a margin. Upgrading from the stock cable to any of the cables we tried (including the DIY CAT6) will give you a much improved transparency, detail, and soundstage.
The first step up from the stock cables are the CAT6. The CAT6 DIY cable had a noticably large soundstage, bigger than all the cables in this review. Its sound signature is mostly neutral, though it tends to be a little bit on the warm side. Its weaknesses, however, is refinement. The sound from the CAT6 is noticeably rougher and less refined than the more expensive choices. Another problem with the CAT6 is that the cable is very stiff, and not very convenient for headphone use. Overall, however, for the price, the CAT6 can be a very shocking improvement over your stock cable.
The Apuresound cable has a distinction in that it’s the most laid-back cable in the review. Keep in mind it’s not a slow, boring, or recessed laid-back, but it’s like taking two steps back from the music so you can examine everything better. It’s a very enjoyable kind of laid-back, even with the already laid-back HD650. It also makes the slightly forward HD25-1 more neutral and more enjoyable overall. Normally when a certain frequency range is more forward, that frequency range takes the spotlight and you cannot hear the other frequencies as well. What we love with the APS is that it results in a clearer presentation of the entire frequency range.
Opposite to the Apuresound, The Equinox has a more forward sound. Some people with a preference for this type of sound will prefer the more “exciting” Equinox over the “laid-back” Apuresound. Paired with the HD650, the Equinox adds a nice sparkle in the high frequency. Keep in mind that when talking about cables, the description of “laid-back” and “forward” means a very small adjustment, rather than sound signature changing adjustment. All of these cables are still mostly neutral. So when we say the Equinox pushes the high frequency forward, it’s might be a two steps forward, whereas a Grado might be a 10 steps forward. The laid-backness of the APS, or the forwardness of the Equinox, will fine-tune your headphone rather than rearrange your headphone’s presentation.