Trouble importing Sony mini dv audio to iMovie '09

Folks: I'm running Mac OS X (10.7.2) and iMovie'09 on my 27 inch imac. I'm using a Sony dcr-trv19 that is connectied via firewire to the camera. The audio, overall, comes in synced fine; however, there is clipping at the higher frequencies that is really annoying. The only way to describe it is that you lose anything above 15hz or so. So every "S" is flat and you get the digitized effect on most words, etc. I've listened to the source tape via the camera in playback to my headphones and do notice that occassionally the camera picked up a bit too much audio, like it is maxed out or as if the level was too high and it hit the red and then ditigized. But that is seldom when compared to the overall level on the iMovie version where the majority of "S"s are cut. Almost like sibilance effect on the digital side. There are no apparent audio import controls to bring the level down, when importing, etc. What are my options to try to improve my import qualities? I've considered upgrading to iMovie '11, but not sure it gives me more import power. Thoughts?