Sound Redirector is a simple appliacation to redirect
wavein to waveout.
Any wavein source and any waveout output can be selected. It's especially useful on WinXP and earlier operating sytems, since vista/Win7 new audio stack supports this functionality natively (but not trivial to find it). In spite of this the program naturally works on vista/win7 too. The most evident scenario to use the program is to connect an analog set to line-in (eg. old walkman). Mute the line-in playing source, and enable the line-in recording source, then start the program and choose line-in for input. Then you can use equalizer, noise filter and other effects
your sound cards provides on wave out, but most likely not on analog line-in.
A bonus feature is the change phase
processing that helps on old casettes where
the phase is not right. You can only notice this error if you have a subwoofer for bass
( the bass is very weak). Classic 2 speaker setups not affected since the left and right channels are separated fully.