General Discussion
In reply to the discussion: God turntables sound freakin' good [View all]hifiguy
(33,688 posts)The massive amounts of negative feedback (30-50 dB) in the circuits of those big solid-state amps of the 1970s and 1980s to get those superficially impressive THD speca made them sound dead and just plain crappy; the feedback sucked the life out of the music . A tube audio - not guitar - amp is usually rated for power of X watts from n Hz to q kHz at 1-2% distortion. The simple fact is that the human ear "hears around" the type of distortion produced by a vacuum tube, but not that produced by a silicon device.
Best practice for modern tube high-fidelity amplifiers is ultra-high quality coupling transformers and minimal global negative feedback, as in 1-3 dB. And many manufacturers, VTL prominent among them, allows for adjustment of the feedback in discrete steps to match best with the speaker you pair the amplifier best. And yes a change from 1 to 3 dB in feedback is wildly audible.