Digital cables need to be identical

I just had a little digital epiphany: I had set up my system by having the clock fed to the Etherregen by a Shunyata clock Sigma cable (on the assumption that the best cable should go upstream) and clocking the dac via a Sommercable BNC cable. Sommer doesn’t sell to the audiophile market but much rather caters for studios and live music. When I swapped the Shunyata cable out for a second, same length Sommer BNC the sound improvement was staggering: tighter bass, much deeper soundstage, stronger and more punchy bass and incredible clarity in cymbals. Lesson learned: no use of different digital cables in the same system.