It depends on the design. An OTL will vary in output impedance based on the tube which in fact does change the sound. A properly done transformer coupled design should sound close if not indistinguishable from an also properly designed solid state design.
Effectively, one can make it so tubes do or do not make a large impact. The problem is sifting through marketing BS claims and the objective results.
Quote:
Originally Posted by
Willakan 
Bleh, tube amp signatures, whilst probably exaggerated, are fine compared with the utter confusion that is the world of opamp sound signatures. Incredibly, discrete opamps always sound better, even if they measure terribly! (cough AudioGd). IC opamp opinions seem to vary - on some boards people suggest that X rolls off the treble, and all the new people who try X find themselves in agreement, whilst on another board X boosts the treble, which of course everyone end up agreeing with. A cynic might ponder the effects of expectation bias.
Tube amp changes, which do at least make sense, are probably mainly frequency response variation, unless one set of tubes has stupidly high distortion I suppose...
To feed the paranoia of opamps, the Benchmark DAC1 uses the NE5322. They found "audiophile" approved opamps caused lots of issues and that upgrades performed using them ruined performance. Even better, look-up the history of the Gain Card which was widely applauded by the audiophile community . . . till they found out that it only had a ~$15 opamp in a minimal circuit.
Also, another issue with opamps rolling: oscillations. Not all opamps will work like they should in all circuits . . . some circuits if not done with care will ultimately kill the opamp.
Consider me part of the cynic group: I definitely expect placebo in lots of cases. Especially seeing things like the Carver Challenge a while back.
Edited by Shike - 6/21/11 at 4:55am
