Uh oh.

Hope the quality of the audio isn't entirely critical... Cleary, I assume you're familiar with the phrase "you can't polish a turd?"

So we're salvaging the audio are we? Well, I can make some suggestions. It's tinny, right? That usually means that there is a lack of bass frequencies, and probably an oversaturation of high frequencies. You could try a bass booster. As well, probably the most useful thing with be an eq, graphic or otherwise. Try messing around with one, trying to rectify the loss of bass frequencies.

If you're trying to have the best quality audio you can at this point, there's something about eq's that you should think about. You won't want to amplify the select frequencies. Rather, you'll want to decrease the volume of the higher frequencies you don't want. This would prevent clipping. But it might not be necessary, it's hard to say without experience with the audio itself.

Hope that helps!