I'm getting a low but discernible hum on my 990's 7.1 channel analog inputs. I've never noticed this before, but then again I've never used the 990's 7.1 direct mode before, either.

I assume this means I have a ground loop somewhere... does the standard method for finding the ground (unplug everything, plug one thing in, test, plug another thing in, test, etc.) still apply?

Sounds like a ground loop or something messing with the analog cables between your source and the 990 (power cord, etc). I'd start by seeing if tidying up the cabling between the 2910 (or the XA2) and the 990 affects it, then start on the standard ground hunt that you described.

Scott,

I had a hum on my 990 once I started to use it as a dvi switcher. This thread is where it was discussed. Basically my hum was coming from two locations, the sat/coax in to my HD tivo, and the ceiling mounted projector being plugged into a different outlet than the rest of my equipment. The hum came back about a month or two ago but only on the center and surrounds when using the analogs of my hd-a1. I traced it to the power adapter for the 7" b&w tv I put in my rack so I could see the 990 setup menus and the tivo screen without turning on the projector. The power adapter dropped a bit, and was sitting on top of the analog cables for the surrounds and center going from the hd-a1 to the 990. Hope this helps some.

John

^^^ Bingo! That's exactly what it was in my case... when I was moving my A/V rack to make some changes, I didn't notice that the two DirecTV coax cables shifted position and were touching the phono cable bundle running from the Blu-ray player to the 990. All I had to do was move the coax cables and blissful silence returned to my speakers.

Excellent! That sounded very similar to a hum that my center picked up a few years ago, which ended up being due to a couple small power cords that had shifted a bit and gotten just enough closer to the speaker cable to give me some grief, so I had hoped it would be a simple fix like this.