dsp chung is a free universal dsp sound effects program for your computer .Chooze the input sound port (for example the line in entry of an external usb sound card) then dsp effects (autovol/compressor , reverb, automodulation,plugins) will be applied and sent to the selected output sound port (for example the system mixer) . The program is written in compiled freebasic , source code is included in the zip file.
I use it to add effects to my new ctk6200 electronic keyboard.
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https://chungswebsite.blogspot.fr/search/label/dsp_chung