This piece on phono preamplifiers, which originally appeared on our previous website, is written from my personal experiences with gramophone (phonograph) records which started in July 1969 (at the age of 14), and my subsequent work with AV equipment during the 1970s . . .
Analogue audio signals (mainly from vinyl these days) are not constrained like digital audio signals, so they need headroom to expand into.
Think of a digital signal as a 14 ft 4 1/2 in double-decker bus. Will it pass under a 14 ft 4 1/2 in bridge? Yes it will. In real life however, it would probably take the paint off the roof.
Now think of the road underneath the bridge being bumpy...
You know you can't fit a square peg in a round hole - although it might go in it would not be a fit - and so most people are really-sensible. But when it comes to valve amplifiers I often find common sense goes straight out of the window.
When something doesn't work it cannot be the valve amplifier's fault - it simply can't be that - can it?