[LDS]

I'll try and explain how I set mine up.

1. Go to setup -> hardware and click the 'monitor' tab. Choose your output format from the dropdown menu in the 'main' column, then configure your speaker order by dragging the L, R, C, etc boxes around. Mine is set to L, R, C, etc rather than the default L, C, R...

Note that the 'Alt' column can be used for a 5.1 stereo down mix. Select stereo in the format column, and drag the L and R boxes to match those of your main speaker outputs. Then select "fold down between CR Paths" under the Control Room Fold Down heading. If you hit the 'Alt' button on your omni, it will fold down your 5.1 mix to stereo.

2. Hit the "main" tab, and make sure your outputs are corrected assigned to Monitor 1-2, Monitor 3-4, Monitor 5-6, Monitor 7-8. And choose what inputs you want to plug in your OS system sound (ie. input 1&2 = analogue 1&2).

3. Hit the "Mixer" tab and make sure "Mon" and "HP" are selected under the channel labelled "Analogue 1-2". Doing this means you will hear your computer sounds through your omni even when Pro Tools is closed. I allso make sure the "record/input monitor enable:" dropdown menu is set to Mutes Mixer Inputs so that I don't hear the same audio twice if I want to record those inputs through Pro Tools.

4. Go to setup -> I/O. In the outputs tab you should see your new monitoring path with a greyed out "monitoring" written in the output assignment. From here, you need to assign your default output bus in the bus tab to that new output. Find your output bus and choose your new monitor path under the "mapping to output" column.

From there, you should be good to go. It is unclear from your post, but if you have a default output mapped to the HD I/O it is entirely bypassing your Omni and the monitoring controller. You need set your output bussing to the monitor outputs of the Omni.