Also since D2H is going into AVR directly so instead of repeatedly selecting DD for HD channels,set the default audio out of set top box to surround.This can be done from Setup
Menu > Setup > Installation > code 1234 > Box Setting > TV Settings > Audio Output >Surround
That ways you should automatically get DD for True HD channels (Apart from & pictures and History HD) and 2.1 for rest SD and HD channels
I have connected D2H white STB to AVR via HDMI. Done the above setup in D2H menu. Now I could see "Dolby Digital" for some of the HD channels.
Other channels it is "PCM". Could not actually test it is real DD5.1 or not as I have only fronts now. So I guess DD is available over HDMI and no coaxial connection is needed from D2H to AVR.
Any idea on what is the difference between "SURROUND" and "AUTO" in the Audio output setting in D2H?