The K3 is fine. No noticeable noise floor or weird noises at 60-80% on balanced output. Bass boost is clear. I bought the XS new for like $400. (I said $500 as reference price). Maybe i just had high expectations due the reviews and comments, But it's definetly better than m50x, like... everything. bass extension, mids, highs, soundstage, comfort. the sibilance and bright is gone compared with what i feel on m50x. But i think was just that. too high expectation.