[Otto]

Hi Mike, and welcome to the Shack!

There really isn't material recorded/mastered in 7.1 (actually, there might be a thing for 6.1 in DTS, but that doesn't matter). The extra two channels are generally "derived" from the 5.1 signal when processed by the receiver. Most of us use a digital connection from DVD player to receiver. In that case, everything will be taken care of for you, as the receiver is doing all the processing.

I have never used the analog 5.1 outputs on my DVD player. The only way I would do that is if I were using a BluRay/HD-DVD player with a receiver/pre/pro that did not process the audio via HDMI.

I'm not sure why the receiver would be engineered that way necessarily, though. Actually, I'm not sure if it means ABSOLUTELY, DO NOT connect anything to the Surr Back L/R jacks (these are speaker outputs, I'm presuming), or if it meant to say that "you will not get anything out of the Surr Back L/R channels because the input you are providing is only a 5.1 set." If you were using a DVD player with 5.1 outs to the receiver and another DVD player with a digital connection (just for example) and you had 7.1 speakers, you could indeed get signals from the digitally connected DVD player, but not the 5.1 connected DVD player. In that case, I would guess that your Surr Back L/R speakers would simply be silent during 5.1 operation, and no damage would occur. If they are saying that damage would occur, then I would keep shopping, as I would not consider that a well-developed receiver.

Anyway, the bottom line is that you will end up connecting the DVD player to the receiver with a digital connection (either optical or coax) and all this talk about using the 5.1 analog outs is moot.