Does the HD7 have a headphone jack?
 

Cannot seem to find an answer to this.

A/V jack
 

The a/v jack can be used for the headphone jack. Get Steve's book it has diagrams how to build an adapter from ratshack parts so you can plug headphones into it.

Thanks for quick reply. Since there is no manual control over audio levels, are many people using a Beachtek or similar?

I do. It works wonderfully. Mine is a Sign Video XLR adapter, just as good as the Beachtek passive adapters and a lot cheaper. However, should you want to connect the XLR output of an audio mixer to the Beachtek/SignVideo adapter, be cautious! Most audio mixer XLR outputs are actually line level at +4 db. You'll have to either find or make an XLR to 3.5mm mini-plug adapter and use the line level inputs instead. Those mixers that can send out a true mic level signal are clearly labeled or have a mic/line switch clearly associated with the XLR outputs.

How are you monitoring your sound? Are you using the adapter described above?

When I do feel the need to listen to the camera's audio I do indeed use a home made adapter as described. Whenever I use either my Sign Video XLR adapter or an external mic listening for distortion is essential. However, when I am using the camera's built-in mic I usually don't concern myself with monitoring audio. But, the ambient audio has to be at comfortable normal hearing levels. Anything really loud, like a siren, a really noisy city street, a lot of people talking in a hotel lobby, a wedding reception, etc, all have a huge dynamic range of sound pressure levels demands an external mic and some kind of attenuation.