I bought this cable with the Sennheiser connections, because I have a Sennheiser IE600 IEM. My main priority with this purchase was a good fit with my IE600, because the IEM uses a slightly different MMCX connector. I have never spent this much money on a cable before, but options are limited for the IE600, so I decided to take the plunge.
The Ethos cable I received fits my IE600 perfectly. It is more snug than the original cable that was included by Sennheiser. If you are looking for an IE600 cable that fits, I can confirm that this one worked for me. I am giving this cable 5 stars because it does exactly what I bought it for.
Other things I can say is that the cable feels nice and thick, it does not tangle, and it is pleasing to handle. The white color is attractive.
Not cable-related, but Null audio sent the cable in a nice leatherette case. The leatherette case was inside of a nice embossed cardboard box. I now use the cardboard box to store my IE600s (perfect size). I use the leatherette case to store a different pair of earbuds. In other words, the packaging and unboxing was very nice.
For reference, here is exactly what I ordered:
1x Ethos Series MKVI Premium Upgrade Cable for Headphone | IEM for $0.00 USD each Headphone Connection: Sennheiser IE300/600/900
Stereo Connection: NL4 Rosegold 3.5