I use a iPhone running mainly Plexamp app to stream from my personal library which is mostly full res ripped CDs . There are some mp3s in there as well that I acquired and those sound ok but yes thinner and less dynamic overall. I cast to Cambridge evo 150 via either google cast or airplay. Have done some quick compares and no big differences jumped at me but will give it some more attention and see. Fwiw it is airplay 2 that does cd resolution and my app indicates that is the case when playing either way.
the Evo can stream higher res than cd and I have found a couple internet radio stations that do that. Those generally also sound very good sometimes better sometimes not noticeably better than CD res…depends mostly on the source material playing more than merely the streaming resolution. In any case there are differences but nothing bad so it often becomes a matter of cutting hairs to decide which is best, so I tend to not care much, as long as the music is playing loud and clear.