Program DirecTV Remote for B&K Ref 50 Preamp

Just got a new DirecTV Genie system to run my home theater through a B&K Reference 50 Preamp. No one seems to know how to program the DirecTV remote to work with the Ref 50. It does everything with the system except the sound. By the way, my previous DirecTV HD DVR's remotes all worked fine with the Ref 50 (after I found the code on the Internet - unfortunately I did not write the code down.

Does anyone have any ideas for program codes I might try to get this DirecTV remote to do all functions, including sound? I have the following ideas so far: 30701, 30702, 30820, 30890. I'd be happy for any suggestions, even guesses at this point. I only need sound and mute.