I'm feeling pretty stupid here. I cannot get my HD-P2 to meter anything via the digital input from my V3. But I managed to do it two weeks ago. The story:
I have two HD-P2s -- one is the pile of rust that has been discussed at length in another thread, but which is fully functional, and the other is a second used one I picked up in the yard sale recently as the eventual replacement for the pile of rust. I bought a V3 about a month ago in preparation for one particular taping endeavor that was going to require the quieter preamp than the HD-P2 provides. The day the V3 arrived, I hooked it up to the newer of my HD-P2s and was getting a digital signal without too much effort. No problems.
Fast-forward a few days and it was time to leave for vacation, which is when I was going to try to some nature recording (coastal Maine -- crashing waves, etc.). At the last minute I decided to take my old HD-P2 since I was going to be using it outdoors, and it has always been fully functional (didn't want to risk messing up the "new" one). However, I had never used the digital input on the old one. I climbed out on the granite cliffs, clamped to the rock, got all my connections made....and nothing. The V3 was metering just fine, but nothing on the HD-P2. I figured that the input was bad on my rusty HD-P2, went back to the hotel, found a Radio Shack, overpaid for two cheaply-made XLR cables, and set everything up again the next morning going analog out of the V3. It worked fine.
So now I'm just getting around to investigating what the problem was with the digital input. However, now I'm connecting it to my "new" HD-P2, which is the one that I got working before, and I cannot get anything to meter on this one either. What am I overlooking (that I apparently didn't overlook before)? I've got the input source set to S/PDIF (instead of Analog/Mic). What else do I need to tell it? I can't find any other settings in the menu that look like they need changed, and I don't remember changing anything else when I got it to work before.