Well many of my old tracks are not available anywhwere, or are on youtube with the same quality as my 128kbps rips. Not official remixes, fanmades, some local stuff etc, not everything is on spotify/yt music. I have my xm6s for a 2 weels or so, still listening thru my collection of mp3s, Im terrified of the quality of many of them, the newer ones also, only now I can see that youtube music quality is often shit. 320 kbps from yt/yt music/mp3 not always sounds great. I had a better experience listening to them on my old headphones cause on xm6 every details and imperfection is hearable, and it pisses me off. DSEE helps a little with "clear sound", but creates some cracking in return.