troyp42 wrote:Well it works with the headphone jack and built in microphone selected but the buzzing and noise is shocking even with the noise gate turned right up.
Ok, well at least we're getting somewhere.
So, is the buzzing/noise coming from your guitar amp, once the signal has made the round trip through the iMac and software? Are you using the AmpliTube app or Garageband?
It may be useful to take your guitar amp out of the equation for the moment and check to see what's going on inside the software by listening to the output of the iMac using headphones. Now you have got the iRig being handled as a microphone input by the iMac, you have got a number of different places where gain is being added and so it might be a case of going to each one in turn and finding out what is adding the noise.
As far as I can tell, you've got the gain control on the iRig itself, in System Preferences you have an Input Volume Level for the 'mic' and then you have an input level on the AmpliTube app. All of these will have an effect even before you get the signal into your virtual amp where more gain (and noise) could be being added depending on the setup used and then the signal gets back out to your guitar amp, where even more gain can be added. I'm afraid it'll be a little bit of trial and error, but proper gain staging will hopefully minimise the noise.