dont use Optical opposed to RCA

ive got a Bluesound Node X and using Qobuz streaming service,i had a problem i could not play the higher res music only 44khz,ive just realised why i was connected via Optical output and the max is 96khz where if you use RCA you get the full 192khz and i can play all music ,so best not to use the Optical if you want the best quality