Hi. I have the same problem as you with the HDR-HC9 camcorder. Recording through micro-making is rubbish: Lot of background noise, Voice distortion, Huge loss of quality. We have tried everything: With condenser mics, Without capacitor, Adaptions xlr to mini-jack, Etc, Etc.
We are adopting the solution is to use a digital recorder SWISSONIC mdr-2 and then edit the video with SonyVegas. This recorder is very inexpensive compared to other, But has the advantage that can connect 2 jacks for mic and has regulatory signal for each micro. This feature is not famous zoom h4.
Greetings