Thank you very much. With that precise information, now I am sure that I am going to buy the Sennheiser's connectors and make my own cable. I misunderstood the litz cable, and when I searched better on Google, I remembered that i fought with that kind of cable some years ago repairing some friend's IEMs, and I know that it usually is very difficult to solder.
By the time, I'd prefer not to cut the equinox cable because it scares me to cut a such expensive cable .
I saw the 1.4 and 3.5mm cable in the link you wrote before for about 20€, and I think that I am going to try doing mine, because I only need the Sennheiser connectors to have the cable complete. Maybe I will finish buying that cable, but first I want to try doing my own cable.
Thank you for your experience, is very usefull. The previous plan was cut the original cable and use a male and a female 3.5mm connector. This way I would have obtained a 1m cable with 3.5mm and an extension/adapter with the 6.35mm male and a 3.5mm female. Anyway, I am agree with you about the litz cable, so I will make my own cable.
Here a link with a Sennheiser cable comparison:
https://www.headfonia.com/sennheiser-hd-cables-comparison/
I have read other comparisons with graphics and measurement analysis, and similar results.
Thank you to both for your help with this subject. I am still a bit new in this hi-fi things
No problemo, good luck!