In my experience, a high quality CD Transport, not necessarily expensive one, can make a significant difference in sound quality. The key is in the chain; namely, Transport, Clock, DAC. Personally, I use a Pro Audio CD Transport that has I/O for Clock, AES/EBU, Coax, Optical, XLR Analogue and more. It also has its own DAC and so comparing is quite revealing! To be fair and because of its Pro Audio pedigree, I configure my preamp to attenuate to Consumer Grade line level to compare with sources such as the WiiM.
In practically all cases, feeding my CD Transport into any one of my DACs including the WiiM almost always sounds better than any other digital source. Those sources include streaming from PC/USB, HDD, wireless to name a few. As to why that is, I am at a loss. After all, digital is digital; or is it?! In real world use, for whatever reason, Redbook CD in pure two channel stereo, properly configured as mentioned above, rivals just about anything I have heard. A three dimensional sound stage with wide and deep imaging and depth is just astonishing to experience. The only other medium that may sometimes rival an excellent digital rig is, yes you guessed it, vinyl record playback. However, that kind of rig also has to be properly configured to yield similar astonishing results. But it is achievable, albeit probably with bit more expense!