If you have time and interest, go through this thread
https://www.whatsbestforum.com/thre...-ocxo-10m-clocks-shootout-op20-vs-op17.26610/
It is difficult to convince someone without listening it yourself. With so many people having the same positive comment on a high quality reference clock, it is a strong evidence that you should have faith on.
Put it in simple term, the sound quality of DAC depends largely on the accuracy of the clock. The better the clock the better the sound. It is that simple and we have not hit the ceiling yet. If an even better clock comes up in the future, the sound can still improve. So far, the best I can find is Cybershaft OP21A.