I found this table, on a professional review of a Denon receiver that is rated 150 watts / channel (8-ohm).
You can see the entire review here:http://www.audioholics.com/reviews/amplifiers/denon-poa-a1hdci/pao-a1hdci-setup
Now... That would suggest that our assumption was right, and 0dB really means the rated power output and distortion.
And if that is correct, you are right to compare the two receivers, if you are using the same set of cables / speakers and the same listening position. It would be possible to do it that way, but you really must set all parameters that can affect sound level equal in both receivers (like DSP's, EQ, YPAO settings, individual speaker level, bass / trebble level, etc, etc)... There are many parameters that would have an effect on your comparison. So, if you could really find equal paramenters for both receivers, I think you can compare their amp power, YES, if using the same speakers and cables, and listening position. You would be able to measure SPL and compare them.
NOW, there is something I didn't expect here. Look at the -10dB wattage in that table (8-ohm speaker). Thats 15 Watts. LOL
It just can't be, something is wrong. There is absolute NO WAY, that if I set my stereo towers at -10dB on this receiver, it would only be using 15 + 15 watts. NO WAY.
-10dB is house shaking LOUD, it can't be 30 Watts only. Just think about a 30watt lamp LOL... NO WAY.
I hope someone can explain that
I would expect much more than 30 watts at -10dB in a 150 watt per channel receiver. Of course the math is correct, since -10dB is 10 times less than 0dB, so 15 watts is 10 times less than 150 watts (rated power). In math terms, yes, it should be 15W ONLY @ -10dB, but I DOUBT this is real, it just can't be... Like I said, -10dB is LOUD AS ****, no way its 15 + 15 watts only.
Now I am even more confused! HAHA!