OT: S/N-Ratio measurment - help

[Alex Stettler]

Hello


I've got a somewhat OT-question: Does someone know, how I could measure
the Signal/Noise ratio of an amplifier, without the need of expensive
audio-analyzing meters?
It would be really great, if somebody could help me.
It could also be a schematic for a circuit or something like this. I'm
an advanced electronic hobbyist, so this shouldn't be a problem.

Many thanks in advance

Alex