Surround sound configuration

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hi
does someone know how i can select that AC outputs Surround sound? I use it with Win10 and in the Option section of AC i did not found any parameter where i can handle the speaker configuration or something else. I searched also the ini files but did also nothing found.
Any ideas?
My sound card is a Xonar D1 and in the Test of the Soundcard the Surround sound did work.
thx for your help
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