I want your advice for a good replacement cable for my fidelio x1. what do you recommend?
One of the best digital and analog cable manufacturers there is
Mediabridge 3.5mm Male To Male Stereo Audio Cable (4 Feet) - Step Down Design for iPhone, iPod, Smartphone, Tablet and MP3 Cases
I believe this to be the absolute best for the price. I haven't found anything better at the same price-point. Just look at the reviews.
Excellent build-quality, aesthetically pleasing, functional, cheap. You can't go wrong.