Have the headphones to a FIIO X3 and a Cambridge Audio Azur 740A respectively compared with an Audio Technica ATH-M50 and was sorely disappointed. The sound of the HP20 is extremely much treble, bass is almost non-existent. Of course the comparison with an over-ear is unrealistic, but the sound of the HP20 also appears extremely thin without direct comparison. From my perspective, the HP20 for the performance offered is extremely overpriced (or my copy is defective).