As said in the title, I think the best feature of these IEMs is the fantastic sound quality. Every frequency is clear, bass is very present and powerful. As a bass player, the massive sound of these in ears really helps with the feel on stage when there is no amps to feel the rumble of my instrument. Build quality is ok, but the cable could be a bit sturdier. In terms of sound isolation and comfort I found these to be a hard fit for my ears, even after trying all of the available ear pieces. It is not bad, but definitely a downgrade in terms of comfort from my previous IEMs (Shure se 215).