The Klipsch IE10s have excellent bass and excellent sound isolation for those who can get a seal with the available tips. Their mid frequencies can get muddled and it the distortion I have measured is higher in the mid frequencies than in the low. However, these headphones don't have low bass or ultra low bass. Translated, they have excellent bass down to two octaves below middle C, the output drops for the next octave and isn''t there at all below 32 Hz. I have two other IEMs that have excellent response below 32 Hz, one is no longer manufactured, however, and the other has it''s own built-in DAC (Z:ero Digital Earphone by Zorloo), the point being that ultra-low bass output is possible for IEMs.