Some PC’s has a line input direct and other only has a headset input where you need use a speaker – microphone splitter to access the line input.
Note also that microphone input may have a 5V DC which means that your line signal to the PC must be AC coupled.
(I have not been able to find a inline box which makes a DC isolation, DC filtering but they are available)



We want to have a good beat signal and this can be difficult to achieve.
If you have drum signals then you can mix an output with a clear drum signals for the S2L only.
Another idea could be using a keyboard aux output setting up a click signal which gives the beat.
This is normally also used by drummers to get time sync with the band.

Also if it is possible then it may be an idea to make some low pass filtering on the signal.