We don't know that, different test benches use different methodologies, if the current Denon, such as the X4800H or Marantz Cinema 40 were tested the same way AVtech did back in 2004, they might be able to get the "Pass" grade too. May be Amir could do one of such test some day, then we'll know.
Integrated amps didn't always do better in that test, the Yamaha A-S2000 also pass but at about 180 W 0.8% THD, it only better the Denon by a small margin.
One Krell integrated did about 180 W into 8 ohms but dropped to only about 130 W 1 ohm, worse than the Denon!
The Onkyo NR906, that should be very similar to the 805, 875 etc., did very well in the 4 ohm tests but got the "failed" grade for the 2 and 1 ohm test, with no explanation given, my guess (only guess) is it might have to do with how the protection acted, e.g. too fast?? If not the protection, I am sure those heavy weight Onkyo could do at least 200 W into 1 ohm for the same duration they used on the other duts.
The bottom line, is, such so called high current tests, as well as the claimed capabilities are tricky stuff, it has a lot do with the test conditions, one being the duration of such tests.
Another popular integrated amp, the Marantz PM7003, so presumable would apply to the 7004, 7005 etc., too, failed the 2 ohm test. If one spent time reading, one will find that the belief that integrated amps are always, or even in most cases, more "powerful" than AVRs are sort of a myth, in the case of 2 channel stereo use cases, obviously.
