what exactly can the mixewr set?

[Jan Stary]

Hello,

I am using a SoundBlaster AWE64 via sound/snd_sbc/snd_sb16 under
FreeBSD 5.4-RELEASE-p6. My mixer(8), when called without arguments,
says

Mixer vol      is currently set to  80:80
Mixer bass     is currently set to  90:90
Mixer treble   is currently set to  94:94
Mixer synth    is currently set to   0:0
Mixer pcm      is currently set to  83:83
Mixer speaker  is currently set to   0:0
Mixer line     is currently set to   0:0
Mixer mic      is currently set to   0:0
Mixer cd       is currently set to   0:0
Mixer igain    is currently set to   0:0
Mixer ogain    is currently set to   0:0
Mixer line1    is currently set to   0:0
Recording source: mic

I can understand the obvious stuff, but what is
igain, ogain and line1? Tweaking them during
various playback/recording situations never
seems to make any difference.

	Thanks

		Jan