Yep, I just got mine today and have the same issue. I also plugged in my Bose headset and found the same thing. No idea how to fix. All of the audio, whether from mp3, pandora, youtube, etc sounds like it's a really low quality mp3.
Sometimes my sound is staticy... if thats a word. How about full of static lol. But really, it stops if I reset the tablet or stop and re start the streaming music so maybe its a software issue?
Well, to add to the description... Since we all hear differently,
I compare the sound to that of playing an analog record in a tunnel.... In a snowstorm.
Or something like that.
Either way, it's not acceptable.
-g-
A hard reset (holding the power button for ~10 seconds) seems to have fixed my issue. In response to the comment about quality being subjective, trust me, nobody would think what was happening to me was acceptable. You'll know it if it happens to you.