Funnily enough I was just about to write about cables too. Early on I replaced the stock tips with Final Type E tips which fitted and sounded much better. I wasn't happy with the cable but lived with it for a while until it bugged me too much so I researched online and more people recommended the Ethos Series Mk V cable for the IE600s than any other so I ordered one.
It took a while to get here and was quite expensive (c. 90 UKP all-in) but I thought it worth it for IEMs costing 6 times the price. When it arrived I listened to a couple of songs I know well then swapped the old for the new and played them again. The simplest way I can describe it is that it was like happily listening to music with my eyes closed, then someone pulling open the curtains that I hadn't noticed were in front of the speakers. Within moments I heard something I'd never heard before and was marvelling at the increase in detail, clarity, positioning and sound stage.
"It's only a bit of wire, it can't change the sound!" I hear someone call from the back. Tell that to all the people who commented on the Null Audio page and anyone who has tried it. It can and does improve the sound, an easy 90 UKP upgrade in my opinion. I know it's a lot to spend on a cable but if you're thinking about a buying new one, DO check it out, I heartily recommend it.
https://www.null-audio.com/collecti...ethos-5n-cgocc-a-silver-plated-earphone-cable
(No connection, just a very happy customer.)