This review is based on use with the Dirac DSP app for Apple i-devices. The sound quality without Dirac isn't far below the sound with Dirac, but is unexceptional, so I don't rate it without Dirac. Portability is great in terms of being a tiny IEM, but it's fiddly to stow away. Sound quality is greatly affected by ear canal seal, especially the bass, and can vary greatly for each user. Generally speaking, the Dirac DSP removes frequency and resonance anomalies, providing great smoothness and clarity, but many users will find the sound a bit bland, so until there are more reports on this sound from other reviewers, I'll just say \"very good\" sound for most types of music.