Alan, I do not have the AVM2, so I cannot be sure they are the same, but to change the surround on mine there are three ways to accomplish this.
1. RS232- I can give you the code set or you can DL this. I am sure you will have no trouble this way.
2. IR- Push mode and enter the number 1-10.
3. front panel-push mode and turn the dial until you are on the sound field parameter you want.

What are you trying to accomplish? Is this the initial setup? Most of time the unit is left on the soundfield for each input. Yes, you have to set the distance/timing and speaker arrangement for each one of the inputs, but ALL good PRe/Pros do this, as you said.

I do not even know if the AVM2 is serially controllable. There is no evidence that it is although the is a db9 on the unit. I could find no serial protocol for this gem. We inherited this lovely piece when the client could not sell his old system with his old apartment. We also inherited an old Sony and Pioneer plasmas. The reason I was there was a minor programming error on my part. The client wanted the all on/off feature modified so it would not work from the any floor save the first ( a tripplex apartment ) and then wanted them on selected rooms on other floors. Somehow in all this I failed to include all the possible button presses for the new, old rooms in the logic. ( they were included, removed and were supposed to be added again. )

"While you're here could you fix the problem...." led me to try to correct the "problem" that only stereo was eminating from his surround location in his office which is the Anthem. When I went to the front panel I could not change the surround mode by pressing the effects button. But you believe that pressing mode and then 1-10 is good programming practice? Thanks for the clue as to how this disaster controlls but discrete surround modes have been around since the the first Lexcon and Fosgate pre/pros. Cheap Japanese electronics had only cycle commands but at least they changed modes. Only an audiophile company would still believe that sound alone matters while egonomic functionality does not. I do understand that this is an early unit. I am not asking for access to all surround modes via IR but a few should be avilable.

I finished a quicky install in the Hamptons yesterday. It was with an intro Integra surround receiver. I wanted access to all features so I used serial control but the remote offers limited surround mode control. Until you hold a high end manufacturer to standards that include 1. reliablility, 2. egonomic and simple control via both IR and serial and 3. good sound you might as well step back to the 80s when remote controls were antithetical to this crowd because they altered the sound.

Could you tell me which cobo of button presses corrusponds to which surround mode? I could spend the unpaid time at the client's home and learn this but if they are going to make it this difficult is it at least in a manual and is this manual available on line?

Alan

Here you go Alan.
[Link: anthemav.com]

They all had serial control, and the commands are almost the same as mine.

The next time you are in front of the unit.
Push "effects" and spin the dial to see if changes the sound field. The remote will do the same with a Up/down.

This is real easy on the remote to get a specific sound field instead of toggling through something you usually cannot see. "effects" or "mode"in my case and the number 1-10. You now will have a chart with the website reference or if you are standing in front of th unit, read the display and decode it.

Better yet, send it a "P1D11" on the serial port and see if Disk input one changes to AC3. Straight through connector, 19,200: 8,1,1 and ASCII LF after the command.

hit it with a ? and it will return the build and firmware revision. Update and charge for it while you are there.