This applies to I-Tech series, but I did get it to work with an XTi, and may work with other devices as well.
Be forewarned...this is not for the faint of heart, and involves much massaging to get working, but it does work!
How to Create a Custom Control Panel to Graphically control Both Input EQ Channels of a Group of I-Tech Amps
1) Create an "I-Tech Master Control Panel" by highlighting all of the amps that you want included in your system wide EQ. Right click, and select "Create Master Control Panel". In my case, the left, right and sub amps. (We also have a center array, front stage fills and rear balcony delays, but I'll treat them separately)
2) Create a Custom Control Panel and leave it empty, ie: don't add any graph from the "insert" list.
3) Now open your "Master Control Panel" that you created for all of your amps that you want included. Open the Input EQ panel and ctr/drag the EQ graph to your "Custom Control Panel." Since I want to control both the left and right sides of all the amps, you'd think that you could now open the "other" Input EQ channel of the Master Panel and simply ctr/drag that on top of the first graph, and select "add", but alas, twas not to be...
4) Now click on the EQ graph that you dragged into the Custom panel and look at the properties (shortcut F4). The second category down from the top of the properties list is "HiQnet", click on "Parameter Addresses" which will open the "Setup Wizard".
5) In Setup Wizard you should see PEQ 1 thru 8. Now starting with PEQ 1, click on it and you should see a column of parameter addresses on the left. These relate to the amps that you included in your Master Control.
(Now you need to familiarize yourself with the filter addresses. The best way is to experiment by creating a New Venue with one device of your choosing. Open the Input EQ of that device, and drag it as instructed above to a Custom Control Panel. Do this with Channel One first, and look at the EQ filter addresses in the Setup Wizard. Delete the graph from your Custom panel, and now drag Channel Two EQ graph to the Custom panel and look at the address properties. You will see the differences this way. Now look at your device in system explorer, and drill down into the device parameters and you'll see a rhyme and reason to the various addresses.)
IE: In the I-Techs, in system explorer, filter #1 is the #1 filter in Input Channel 1 EQ and has addresses in the 5000 range. Filter #1 in Input Channel 2 is in the 5280 range. I looked at the XTi series and the filters are addressed the same for the two channels, but the "Object Address" is different.)
6) Now back to step 5) above, you will notice that the column of addresses all point to one channel of filters.
IE: click on one device and the addresses on the right will correspond to the filter parameters of one channel only. It will be the channel that you had as "selected" when you dragged the EQ graph from your "Master Control Panel" to your "Custom Control Panel" in step 3) above.
Now the magic begins... If you were to click "Add" at the bottom of the Setup Wizard panel, it will duplicate the device at the top of the address column.
Click on this duplicate (which appears at the bottom of the address column), and CHANGE the filter parameters on the right to correspond to the correct addresses for the Channel Two filter parameters. (This assumes that when you originally dragged the graph from your Master Control panel to your Custom Control Panel you had Channel One selected.) Now move this address to the top of the column and "add" it however many times for the number of amps that you are controlling. Now you have to click on each of these added "Channel two" addresses and simply change the "device address" to correspond to each of your amps IQ address.
IE: In my case, in PEQ 1, I have a column of twenty device addresses, all controlling "Channel One" EQ of twenty amps, and my filter parameters are in the 5000 range. I click on the top amp parameter address, and I duplicate this amp with the "Add" button, and change the filter parameters in the duplicate, to the 5280 range. Then move this "Channel Two" address to the top of the column, duplicate it twenty times by using the "add" button, and then change the "device address" in each of these duplicates to correspond with each of my twenty amps. Then I had to repeat this procedure for each of the 8 PEQ bands.
In my case I had to deal with 20 amps, so I had to duplicate 20 amps in each of the 8 PEQ bands to be able to control both channels of all the amps with one Custom EQ panel.
Was it time consuming? Yes, but I can now EQ an entire system of amps, BOTH channels, with ONE Graph panel.
I hope this helps anyone who has been trying to create a "Master EQ" for their system.