75 ohm cable for digital connections. 75 ohm is the standard both for cables and connectors. Anything less causes reflections and degrades digital signal.
optimum length to minimize reflections is 30cm (~12") OR 5 Meters

* Solderless connections further reduces reflections
* 75 ohm SPDIF cable from Gotham Switzerland (as used in some mega$ cables)
* 75 ohm RCA type plugs

You are not hearing what you DAC can do unless you connect with 75 ohm cable and plugs

This is for 1 length 30cm cable completely assembled and ready to use.

Sorry this can not be DIY due to the special tool and die needed to achieve the solderless connections