The IE 400 Pro is a clean sounding iem that is able to provide an agile bass expression, transparent midrange and detailed treble. It has good details retrieval and there is precise articulation. There is an open soundstage. In addition, the IE 400 Pro has solid build quality and it uses Pentaconn Ear connectors. The Sennheiser IE 400 Pro delivers an excellent sonic display with a high level of definition.