I don't understand the role of the preamp and integrated amplifiers. Why don't we use a multiple input power amplifier with variable gain? I know it is possible because I have seen (but not heard) one or two examples. I don't understand the need to have a seperate component to destroy sound quality.
I know previously preamplifiers were primarily for the phono input, but long after this role has passed we were still using preamps. Of course, stand alone phono preamps were always available that could have been used to directly drive a power amplifier. Confused!