The sound quality is excellent. I haven't have any scratchy/garbled/echoes while listening to music and I've had it almost if not at the max! In fact, it is so crisp that I've heard things/pieces in songs that I'd never heard before, and I'm talking about 10, 20 y/o songs that I've heard hundreds of times!
Wow. I am seriously surprised by all the reviews claiming these things have good audio quality. Do not waste your money here. The price is attractive but this is not their best product yet... I have a pair of their "Upgraded E8" headphones and the audio quality (though hardly comparable to high-end brands) is MUCH MUCH better, and much more acceptable for the higher price range.
It's actually pretty good in my opinion, I love the bass. I've had mine for less than 6 months. The great sound quality gives you an immersive feeling when you are watching movies or listening to music with people you love. Can't complain.
I've been a broadcast engineer for 42 years and what I hear is highly accentuated "deep bass," just as advertised. At mid volume levels, you hear extra bass that, to my ears, sort of muddy the fidelity. The highs are relatively clear, but I would rather hear a flat bandpass. At high-level listening, I hear a bass clipping--gross distortion. In this regard, they're like Beats, and a lot of people like that, even if it's not high fidelity.