Indeed, willemj is right.
And so was Peter Aczel, of The Audio Critic, when he said: “Longtime readers of The Audio Critic know the drill that comes at this point: I repeat, for the nth time, that all amplifiers having high input impedance, low output impedance, flat frequency response, low distortion, and low noise floor sound exactly the same when operated at matched levels and not clipped. (Those who are unable to stomach this simple truth, proved over and over again in double-blind listening tests, should stick with Stereophile.)”
Of course, it's true that certain unique loudspeakers can present loading that will cause good amplifiers to sound slightly different; refer E. Brad Meyer's article that originally appeared in the June 1991 issue of Stereo Review. (More recently reprinted in the Boston Audio Society's monthly BAS Speaker publication.)
And while it may be theoretically possible to construct a vacuum tube-type power amplifier that will initially approach equivalent excellence, that product will also exhibit persistent and continuous degradation from the time of initial turn-on until its ultimate end in cathode depletion failure—barring other modes of premature demise (e.g. open filament, vacuum leaks, gassing, microphonics, atypical distortion, hum/noise). So vacuum tubes are not a wise choice when stable, long term circuit performance is a serious design goal.
And so was Peter Aczel, of The Audio Critic, when he said: “Longtime readers of The Audio Critic know the drill that comes at this point: I repeat, for the nth time, that all amplifiers having high input impedance, low output impedance, flat frequency response, low distortion, and low noise floor sound exactly the same when operated at matched levels and not clipped. (Those who are unable to stomach this simple truth, proved over and over again in double-blind listening tests, should stick with Stereophile.)”
Of course, it's true that certain unique loudspeakers can present loading that will cause good amplifiers to sound slightly different; refer E. Brad Meyer's article that originally appeared in the June 1991 issue of Stereo Review. (More recently reprinted in the Boston Audio Society's monthly BAS Speaker publication.)
And while it may be theoretically possible to construct a vacuum tube-type power amplifier that will initially approach equivalent excellence, that product will also exhibit persistent and continuous degradation from the time of initial turn-on until its ultimate end in cathode depletion failure—barring other modes of premature demise (e.g. open filament, vacuum leaks, gassing, microphonics, atypical distortion, hum/noise). So vacuum tubes are not a wise choice when stable, long term circuit performance is a serious design goal.