You misunderstand the point the test is trying to make and if you look at the statement in the first post there is a caveat, which nicely covers the point in the RC test.
However, pretty much no one uses their amplifiers within these parameters but at low levels (i.e. within the "operating parameters" you will not be able to tell the difference (blind tested of course)
To be perfectly honest, at low volumes I can't tell the difference between the Krell, my NAD C370 and Arcam Delta 60. It is only when played at normal listening levels do the differences become apparant.