I'm not discounting what you're saying, cause quite frankly I don't even speak the language...but how do you account for the fact that I prefer the sound of my Meier Jazz/Grado GS1k when the tube buffer is activated vs when it's only the Meier in the signal path? I think what you're saying may be perfectly valid about the higher output impedance being favorable for the Grado phones, but when you say this accounts for the quality of tubes being misinterpreted I'm not sure I agree. I enjoy headphones and speakers that have a robust top end, to the point where they would even be classified as "bright". But what I don't care for is "harsh"...and over the years I have experienced many examples where the presence of tubes mellowed out the harshness even on poorly recorded material and provided a bit of "warmth". I've also been able to observe different levels of success via tube rolling, which would further indicate that it was a quality specific to the tube that was responsible for the "warmth", not only the output impedance of the amplifier.