...Some audiophiles state that the sound produced with tube amps is more natural than the sound from typical transistor amplifiers, and for this reason more satisfying. Typically, in sound reproduction systems, accurate reproduction of the sound of the original recording is the goal; gross distortion is something designers do not deliberately seek to introduce. At the upper end of audio systems ("high end" or "audiophile" systems) it is debated whether "accuracy" can best be described by measuring a "wide frequency response" and "low measured distortion levels" or whether highest quality reproduction is subjectively determined by listening alone.

Tube amp building and designing is the art of making compromises. All designs distort to some degree. Some designers seek a compromise in the nature of "benign" distortion, others in a design that measures well in standard bench tests. In the high end world where sales pressure relative to perceived performance is high, "how it sounds" can have greater importance than how it measures....