QUOTE(evan smith @ Aug 18 2008, 04:54 PM)

Hello Mike,
Do you have your Alesis microphone selected as the default input device in your System Preferences? Snapz will use whatever is selected there.
Cannot speak about 10.5, but in Tiger, Audio Midi is handy for checking audio out. If input is correct (stated above) and output needs verified, use the speaker setup test. Clicking R or L will hiss on that channel.
QUOTE(evan smith @ Aug 18 2008, 04:54 PM)

Not sure what you're trying to do with the headphones, but there's no monitor option in Snapz if that's what you are looking for. You would not be able to hear how it sounds until after the movie has been exported. Hope this helps

The only good way to monitor that I have used requires; an iMic, Sound Studio (v2 for me. v3 is current), Altec Lansing speakers and/or my cheap RF headset plus the "patch cord box". If using Quicktime? Do not know. I only record audio via SSv2.
What I do is send "built-in" Aout to a 'Y' cable. One branch to speakers, the other to iMic input. This config is std. for recording audio from Real Player for example. Set system volume to 80% and set app volume to 50% record a few seconds (15? 10?) stop and look at the wave form in the SStudio. Level to low? Clipping? Is easy to correct .
If all my ramble has missed the subject? Act II The sound editor can have any input or output. At this point I am assuming WireTap has been checked out by you and doesn't apply to what you are doing. On to 2nd type of config.
Audio in is "YourUSB mic" and audio out is "built-in" in sys pref. In SoundSstudio A-in is the same but A-out is USB device (iMic). Headphones are connected to iMic OUT and SoundStudio "By Pass" is turned on.
The bottom line is; if you do these videos often get an iMic from Griffin. Reason? 1. can record audio track to it's own file for post processing, 2. allows you to cobble a monitor of sorts, 3. just dam handy
Without knowing what apps and hardware are involved this ramble is mainly food for thought and may give you the eureka moment.
Disclaimer: Up to neck in a project and cannot take the time to verify if I recalled all of the above correctly. Pretty sure but it is always best to test and be 100% sure. Great the chain gang boss just twitter'd, fun is over for me, rebooting machine-- testing volume time.
Have fun,
-d