Hi Florian,

Thank you so much for clearing this out! Now I know what to do to achieve what I want. The good old method of mixing audio tracks afterwards :-).

I don't have schematics either. Random Source doesn't supply them with the kits. The only one that is available is from Ken Stone but it may be different from the one of Random Source.
Ken Stone's Modular Synthesizer

 

Best regards,
Karel.