Budget_AudiophileThey are SMSL W6 RCA cables. google it, images, you'll see them used between the SMSL M8 DAC and VA2 hadphone amp. Sold by ebay sellers that sell SMSL stuff.
Very convenient, suitable. if you try finding short RCA cables like this, you'll see; most makes do 1m as the shortest, only a few do 0.5m - and even half a meter would be unnecessarily long for applications like this.