I was looking at 'Audio Electronics' by the late John Linsley Hood this morning
while waiting for the newspaper to arrive, and was amused by this:

" Experiments in the late 1940s suggested that the level of audibility for
second and third harmonics was of the order of 0.6% and 0.25% respectively,
and this led to the setting of a target value, within the audio spectrum, of
0.1% THD, as desirable for high quality audio equipment.
However, recent work aimed at discovering the ability of an average listener
to detect the presence og low order (i.e. second or third) harmonic distortions
has drawn the uncomfortable conclusion that listeners, taken from a cross
section of the public, may rate a signal to which 0.5% second harmonic
distortion has been added as 'more musical' than, and therefore preferable to,
the original undistorted input. This discovery tends to cast doubt on the value
of some subjective testing of equipment."

So the SET set is right. single-ended valve amps are officially 'more musical'.

--
Eiron

No good deed ever goes unpunished.