@sls883 Both! Both is best for me, after quite a bit of experimentation. Holds true for both PCM NOS and OS modes and DSD equivalents, though effect of externally clocking the R26 is more pronounced when using PCM NOS OFF and DSD Direct OFF i.e. internal oversampling ON.
The Harmonic Technology Digital Copper III is an excellent cable, quite a step up from the Gustard C2 and the cheaper but excellent performing LMR400. Ramble Audio HK has the best pricing and shipping cost globally.