Why do mic preamps sound different?
Let's be honest, designing a microphone preamplifier is not rocket science. In fact rocket science isn't even rocket science - just mix the fuel and the oxidizer and set light to it. WHOOSH!
The fundamental job of a microphone preamplifier is to take the signal from the microphone which is low in voltage and not all that strong in current, and convert it to the kind of voltage and current capability required by the mixing console or recorder.
There is nothing that isn't known about microphone preamplifiers, and a designer who makes a bad one is either a poor designer, has to work to a tight budget for components, or is doing it on purpose for some kind of marketing reason.
All properly designed microphone preamplifiers, when used correctly and within their limitations, sound so similar to each other that even bats can't tell the difference. Certainly, any residual differences are orders of magnitude less than the differences between microphones. However, this doesn't necessarily tell the whole story. Preamplifier designers sometimes don't consider the way in which their products are used in the real world, which might be quite different to what they consider 'correct' practice. And then there is the feeling that a mic preamp perhaps should not be entirely accurate, but should purposely be designed to color the sound in some way.
This special feature was inspired by comments by ace designer Ted Fletcher - www.tfpro.com