If I double click on my audio icon in the tray, I get a small box with 5 controls in it. The first two on the left: Volume Control and Wave Balance, are the only ones I get a response from.

The other three: SW Synth, CD Audio, and Line In never have any effect by changing them. How can I tell if they are activated, or, whay are they actually for? The mute boxes at the bottom are not checked.

The controls mentioned are for input volume control, such as a microphone...

Other control is for loudness of the MIDI mapper - try playing some midi files and see how it works.

If you "Open Volume Controls" and go to "Options->Properties", you can tick either "Playback" or "Recording".

Here's what's available on my PC under:

PLAYBACK
Volume Control [the master control that varies all the others]
Line In [adjusts the "Line In" on sound card]
Wave [playback vol of "wav" files]
Microphone [adjusts live amplification vol from "mic" in on sound card]
CD Audio [adjusts playback volume of audio from "CD player"]
Synthesiser [don't know]
AuxB [don't know]
PC Speaker [PC's internal speaker volume?]

RECORDING
Line In [adjusts recorded vol from "line in" on sound card]
Microphone [adjusts recorded vol from "mic" in on sound card]
CD Audio [adjusts vol of recorded signal from audio CD source]
Mixer [Not sure where my sound mixer is]

You need a signal from some source to be able to record it or play it.
The mic for example could be recorded and listened to live at the same time I think.
I remember using a headset with mic and listening to my own amplified voice whilst recording it to a ".wav" file so I could play it back as an answerphone message. [I was trying out the PC as an answering machine when the PC was acting as a telephone. I gave it up as too much hassle, the telephone worked more simply and effectively.]