Types of source or destination lines. The descriptions for these lines have been taken from http://www.borg.com/~jglatt/tech/mixer.htm.
public enum MixerLineComponentType
Assembly: ManagedWinapi (Module: ManagedWinapi) Version: 0.3.0.0 (0.3)
An undefined destination line type.
A digital destination, for example, a SPDIF output jack.
A line output destination. Typically used for a line output jack, if there is a separate speaker output (ie, MIXERLINE_COMPONENTTYPE_DST_SPEAKERS).
Typically a "Monitor Out" jack to be used for a speaker system separate from the main speaker out. Or, it could be some built-in monitor speaker on the sound card itself, such as a speaker for a built-in modem.
The audio output to a pair of speakers (ie, the "Speaker Out" jack).
Typically, a headphone output jack.
Typically used to daisy-chain a telephone to an analog modem's "telephone out" jack.
The card's ADC (to digitize analog sources, for example, in recording WAVE files of such).
May be some sort of hardware used for voice recognition. Typically, a microphone source line would be attached to this.
An undefined source line type.
A digital source, for example, a SPDIF input jack.
A line input source. Typically used for a line input jack, if there is a separate microphone input (ie, MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE).
Microphone input (but also used for a combination of Mic/Line input if there isn't a separate line input source).
Musical synth. Typically used for a card that contains a synth capable of playing MIDI. This would be the audio out of that built-in synth.
The audio feed from an internal CDROM drive (connected to the sound card).
Typically used for a telephone line's incoming audio to be piped through the computer's speakers, or the telephone line in jack for a built-in modem.
Typically, to allow sound, that normally goes to the computer's built-in speaker, to instead be routed through the card's speaker output. The motherboard's system speaker connector would be internally connected to some connector on the sound card for this purpose.
Wave playback (ie, this is the card's DAC).
An aux jack meant to be routed to the Speaker Out, or to the ADC (for WAVE recording). Typically, this is used to connect external, analog equipment (such as tape decks, the audio outputs of musical instruments, etc) for digitalizing or playback through the sound card.
May be used similiarly to MIXERLINE_COMPONENTTYPE_SRC_AUXILIARY (although I have seen some mixers use this like MIXERLINE_COMPONENTTYPE_SRC_PCSPEAKER). In general, this would be some analog connector on the sound card which is only accessible internally, to be used to internally connect some analog component inside of the computer case so that it plays through the speaker out.