Speaker sounds distorted at higher volumes

A few months after I bought my iPad, I noticed that at high volumes, sounds on the built-in speaker were distorted on all applications. It sounded like a blown speaker. I tried rebooting and restoring my iPad to no avail.

The interesting thing is that it only seems to be coming from the left channel.

I went to Settings>General>Accessibility>Hearing and was able to adjust balance.When I set the mixer to right only, the speaker sounds fine (but is only the right channel) It starts to sound distorted as I bring the left level up.

It sounds fine on headphones and bluetooth speakers, no distortion at all.

Any ideas for a permanent fix that allows me to listent to both channels at the same level?