Nick, I looked at the lab tests of the 3808 that Jay linked and then looked up the test of the 7125 by their sister publication
here . It appears that there's practically no difference in maximum power capability for home audio use. They don't always use parallel numbers, but there's enough identity to make the comparison. For example, with all channels driven the 7125 measured 142 watts into 8 ohms, while the 3808 measured at 130.7 watts. With the more realistic for home use 2-channels driven tests the 7125 measured at 189 watts into 8 ohms and 269 watts into 4 ohms, while the 3808 was actually slightly higher at 210.9 and 277.3.
Although you acknowledged that "unused headroom is simply unused", you then suggested that spending an extra $300 for something that wouldn't be used is okay?? Paying for excess headroom beyond what will ever be used is simply blowing money that can be used on something meaningful. The fact should be grasped that buying a 500 watt or 1000 watt amplifier would be meaningless if the headroom available with the 3808(and 7125)was already more than needed.
With respect to the 790, keep in mind that MultEq isn't the highest grade of Audyssey for HT receivers. MultEQ XT found on the 3808 and the Onkyo 876, for example, has more measurement positions and higher resolution filters for more accurate results.
