What's wrong with my audio system?

If not previously restored, vintage audio equipment very often will have, among other problems, leaky or dried-out electrolytic capacitors, components whose leads are corroded or values that have drifted, or show other ravishes of time. These old components may cause degraded performance which will affect the fidelity of the sound your system reproduces. An amplifier may still “work”, but the sound it produces can be muddy or shrill or have other audible defects that will affect the enjoyment of your music. Or the equipment may be completely non-functional, which can be caused by other reasons such as shorted or open transistors, defective vacuum tubes, burned out resistors, or bad connections on a circuit board, etc.