These comments apply except to tube devices, where all sorts of anomalies may alter the frequency response, noise, and distortion. (Yes, 2x6, tube distortion can be heard by many listeners as a positive quality--a so-called "richness" or "warmth" in the bass that isn't present on the original recording. But it's still a distortion of what was intended by the recording engineer and producer.)
In other words, a tube headphone amp has the potential to color or change the sound quality like a tone control or equalizer. I don't want my playback devices, whether loudspeakers, electronics or headphones to color or alter what the musicians and recording engineers intended. The more neutral the links in the chain--the microphones, microphone preamps, storage device, playback device, amplifier and speakers or headphones--the better.
Alan, do you feel that this distortion in tube amps ONLY colors the sound? What about the increase in clarity, soundstage, bass tightness, realism, separation of instruments, and many other sound improvements that many listeners report to hear. These don't seem to be just attributed to 'distortion' can it? Also, I don't think they change the sound in the original recording, but rather they bring the sound
closer to the original recording as it was meant to be heard.
While I do have my doubts about certain drastic improvements one can get with hi-fi equipment, there are too many anecdotal accounts from many listeners, and even my personal experience can attest that what I hear when I listen with a headphone tube amp is not just coloring, but improvement in "sound quality". I will admit there is warming of the sound, possibly this is the distortion as you say, but I can't deny the greater satisfaction of musical enjoyment. Subjective yes and even if it is measured as distortion...
