Not sure if you have a budget in mind, but you can easily spend more on the cable than the Sundara's themselves ...
Personally I've been very happy with Hart Audio Cables, and have slowly converted all of my headphone cables over to Hart, it's made things just simpler to organize
- Made in the USA with oxygen free, Mogami copper
- Sonically excellent with minimal microphonics (e.g. noise when cable rubs against clothing)
- Modular approach - swappable interconnect (6.35mm, 4-pin XLR, etc.) that connects to the headphone cable through a mini-XLR connection
- Lots of customization options for length, color, braiding, etc.
- Affordable - relative to a lot of custom cable makers out there
- Excellent customer service
Example image:
- HC-9 Dual 3.5mm TRS balanced cable - use it on my Hifiman Arya and Ananda (works on Sundara too)
- Pictured is a 6 foot cable with interconnect for 6.35mm, 4-pin XLR, 4.4mm and 3.5mm