Had my um pro 30 for almost a year, but it's only in the last couple of months I started to really appreciate it. I remember when I first had it I thought the bass was a bit overdone and the treble lacked sparkle, but once got used to the sound (though it really took a long time), I found that the treble was there just presented in a more natural way instead of in your face, and the bass was really nicely done to add enough warmth, altogether making it such a musical and effortless listening experience.
I have more expensive IEMs like Andromeda, K10 and U4-SE, all of which destroy the um pro 30 in resolution, timbre and extension, but none of them could really replace it. When I'm doing something and just want some music playing in the background, or when I'm feeling lazy and just wanna lie down and waste some time, I still reach out for the um pro 30 expecting a sound that is cohesive, intimate and fatigue free.