I record before some days on a convert.The problem is the automatic gain control.there need a way to do manuel set of audio level and show with a levelmeter so manual can set the gain.
But i guess this is too much work, and there is not know how can process audio.chdk seem have no audio hook.
to get the bass back is pssoble in some way.use a testtone cd, play it with a headphone on your microphone.and record the video.
Now you need a equalizer to boost the too low frequencies.
On my Ixus 1000 HS, i need set a paremetric EQ with Q 1 at 160 hz with +4 db.And 80 hz i set +10 db.
sound is ok, but the most problem is the as i told the automatic gain control