I collected a serious amount of vintage active (amplifier build in) speakers, so I tried to make a 7.1 setup.
These active speakers monitor their input sound channel, and switch off a few minutes when no activity is seen.
I tested this setup with the soundmax tools for the realtek AD1988 chipset, on my motherboard running XP SP3.
Also a microsoft 7.1 testfile addressed all channels after each other and all sounded OK.

But with Skyrim, the surround channels switch off after a few minutes, which means no sound is sent to the speakers.
Conclusion, It appears that Skyrim does only 5.1 on my 7.1 setup.

Am I the only one with this problem, or is this a game 'feature'.

I have a 7.1 setup as well and never had games using all speaker - they tend to ignore the sr/sl channels.

Skyrim seems to ignore 2.1 setups as well, which is extremely common. I think that's why we get low sound in Skyrim
The game only seems to accept 5.1 setups properly, which is quite a big shame for a AAA game. I wonder how extensive Skyrim's compatibility testing was when they launched this game.

I've never had any problems with the game sound in skyrim... weird when tons of people seem to have a problem with it

I suspected also that the subwoofer channel was hardly or maybe not used, because that speaker also switched off when I set it to 'auto off' (this one has an always on or auto off switch).
So I hooked my scope to the subwoofer channel, and went to 'understone keep/markarth' with its rumbling machine noise allover.
Nope, no activity whatsoever on the subwoofer channel.
So I went to the outside world, and fast-travelled to some location, where I was attacked by wolves, and the sound of a circling dragon somewhere.
Killed a wolf, and almost immediately a dragon fell from the sky, and yes, that drop on the ground showed subwoofer activity, so that channel is used !

More weird, that dragon was already dead and started the soul absorb animation (no subwoofer activity here).
I have seen dead creatures/items dropping from the sky before in Skyrim, usually after a fast travel or leaving a house etc. but this 'drop a dying dragon on the player' is a first time