Q: 2009 24-inch iMac 3.06GHz (EMC no. 2267).   I don't get any audio when connecting my Sony HD TV to my iMac via mini DisplayPort. Is there a fix or hardware upgrade?  I'm using a Kanex Mini DisplayPort to HDMI cable w/ audio support.

Your iMac early-2009 does not support audio out via HDMI.

Here is Apple support document

http://support.apple.com/kb/HT4241

You need to take audio from the audio port out to your TV audio input.

Usually a 3.5 mm headphone jack at one end and R/L RCA plugs at the other.

You can connect the audio from your iMac to your TV using a mini jack (like headphones plug) to rca (regular red and white audio connectors used on every TV,DVD, etc) cable.

On your TV, you need to be able to set the audio for the HDMI input you will use to "analog" and connect the rca end of the cable to the analog inputs on your TV.