Just got my ZS10 yesterday and spent some time comparing with the ZSR, which has been my primary IEM for a while. For my large ears, both feel comfortable but I think it's easier to find suitable tips for a good seal with the the ZSR. I ended up settling on the same JVC Spiral Dots (L) that I use with the ZSR. This is probably the first time where my beloved KZ starline tips were a poor fit with the size L because they were too long and put the ZS10 enclosure too far out of my ear. I tried the M just in case but those fell in, the same way any other non-L-size tip would. The first thing I noticed was that the ZS10 has less mid-bass emphasis than the ZSR, with possibly slightly better extension and generally tighter low-end. This allowed the mids to open up more on the ZS10. Vocals sounded more natural with better separation; solo violins and guitars more easily cut through their accompaniment. Treble is good but haven't had much time to compare for now. The ZS10 is a bit brighter but not overly so. Overall, my impression has been positive and I'm enjoying the ZS10 a lot. However, the ZSR may be more fun on certain styles where a strong, thumping bass is desirable.