The warm in-ear monitoring sound of the IE 400 PRO with its rich, noticeable punch is the right choice for professionals who wish to take their accustomed studio sound onto the stage with them. Even at high sound pressure levels, the IE 400 PRO reproduces its warm sound 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.