The in-ear monitoring sound of the IE 400 PRO delivers a noticeable punch, clear high frequencies and transparent mid-range reproduction. Even at a high sound pressure levels, the IE 400 PRO’s warm sound is free from artifacts and distortion. With the newly developed TrueResponse technology, the dynamic driver measuring a mere 7mm generates tremendous resolution and prevents acoustic stress, even during long periods of use. Distortion, overlapping frequencies and feedback peaks which otherwise occur frequently are no longer a problem. The distortion factor has been optimized to a previously unimaginable 0.08%. The ultra-compact design can be adjusted to fit the individual thanks to the accompanying silicone and memory foam adapters. Easy to handle and robust, the IE 400 PRO reproduces a brilliant sound under extreme stress, and a secure and comfortable fit allows for use hours on end.