Volume knobs: I hate.

To control the volume on a computer you typically have three knobs, and sometimes four:

-- your speakers have knobs
-- your master soundcard volume
-- your PCM soundcard volume
-- the application's volume, before it produces the PCM data

Wtf?

You never know which are line-level, which amplify, which attenuate.

Is there a guide or rules of thumb to setting your volume correctly?