An #amateurradio question: I've read that some hams turn the RF gain down to noise level and turn the AF gain (a.k.a the audio volume for non-hams) up in order to reduce the noise (mostly atmospheric, but also QRM) the radio receives. For people who do this, how well does this work?

I've never operated that way in my almost 12 years of being a ham, but I'm willing to try it. Anything that can potentially reduce noise and/or bring up signals is worth trying in my opinion.