Routing highly depend on the audio application you are using and not all audio applications support such feature. The plug-in is simply able to receive up to 4 input channels and channels 3 and 4 are used for side chain signal. These extra channels have to be configured before inseting the plug-in into the slot.
Which application do you use?
Regards,
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Mateusz Wozniak
PSPaudioware.com