Cool, I read the post but I don't think it's as complicated as they're making it out to be.a very long post about sub/avr tuning but very very cool if u get a chance to read it.
Basically your receiver is outputting the signal at one volume and the speaker (subwoofer) is set to another volume, and if you multiply the two, that's the actual volume.
It's the same thing as having a pair of computer speakers (with their own volume control) plugged into your computer. If you set your computer to 50% volume, and the speakers to 50% volume, then the actual volume you hear is obviously going to be 25%. (That's not exactly how the math works but it's good enough to understand what's going on.)
If you turn the volume way down on the computer, then you have to turn the volume way up on the speakers to get a useful total. That means the signal from the computer is kinda crap, because it's a low level and very close to the noise floor, so it's unnecessary noisy. And plus it's lower resolution. And plus you have to run the amp on the speakers closer to its maximum level, which is the zone where amps perform the worst. So the result is that you're hearing static when it's supposed to be silent and the amp is probably distorting.
So that's why it's much better to run at ~80% volume from your computer (to avoid distortion from the DAC) and control the volume with the knob on the computer speakers.
Similarly, it's going to be better to run your receiver subwoofer level closer to 0 and control its volume with the volume knob on the back of the subwoofer. Exactly how much better, who knows, but it's theoretically better. The only reason you'd want to run at less than 0 is if you think you'll need to turn the subwoofer volume up via the receiver, and I'm not sure why you would even want to do that, unless you're running Audyssey again or something. Otherwise just use the knob?