Actually, there is a lab test on the 3808 here , but it isn't "full" in that the pre-amp output which was your interest wasn't tested. It rarely is tested, possibly because a very low proportion of receiver buyers use the pre-outs, and those that do should almost never have good reason to be concerned about the output level.

Nevertheless, the test did show uniformly excellent results, including power(186 watts into 8 ohms and 238 into 4 ohms)which indicates audibly transparent amplification at all safe listening levels with the M80s.

It's good to hear, although hardly surprising, that providing adequate ventilation solved the problem with the 3808.

Enjoy the music, not the equipment.