Well, that's because people are misreading the graphs if they are saying those measurements are the reason. Here are the specs for the RE-400:
Rated power: 10mW
Maximum power: 30 mW
Assuming that they are accurate specs, it would only take 8mw to reach 111 db. That means if you are listening to them at a little over 100 db average--which is very loud--you still have 10 db of dynamic headroom. 8 mw is below the max output of the DX50 amp according to those measurements where you would have to worry about how the different max output varies with impedance.
So look elsewhere for the reason people don't like the RE-400 with the DX50. Could be that they just don't care for the synergy of the DX50 sound signature in comparison to other amps that they have heard. Or could be that they have convinced themselves that there is a problem because they heard about those measurements, when there's not one
Edited by cel4145 - 7/11/14 at 11:51am