Bought mine 28-10. Returned it the same day. The sound was loud and popping and volume controls where not working. The new iPad was fine.
Now after almost a month of use the new one has the same problem. when I test the system sound it pops and the volume is always loud. Going back to another application after testing the sound, say youtube, there is a popping noise and sound sounds like it coming from a can.
So 10 days of use is not really an assurance it will not happen again.
Than again maybe the problem is solved in a new hardware revision..
At least I can replicate the issue. I will go back to the store today en get it replaced.