If you have S/PDIF ports on the back, then you plug it in there. If not, sometimes there is a spot for it on the mobo, but you need to find the connector - usually from the mobo manufacturer.
The mobo manual should tell you which port it uses when you increase the # of channels. THat's done using the sound 'card's' control panel options. I don't have that mobo, so I don't know what the control panel looks like for you.
I like socket A motherboards as they are nice and stable. I have the Asus A7V133 and all the Asus A7V series motherboards are nice. All of the questions you asked are motherboard specific, which means the best answers to your questions (and the most accurate) are from your motherboard manual . .if you no longer have your manual then you can go to the ASUS website and download a new manual in PDF format. The manual will show you where your S/PDIF ports are; as far as the "second Line Out channel" goes . . it may be controlled by a software program or a jumper on your motherboard . . . but the manual will tell you exactly what software driver you need and / or the details of how to do it.
I like socket A motherboards as they are nice and stable. I have the Asus A7V133 and all the Asus A7V series motherboards are nice. All of the questions you asked are motherboard specific, which means the best answers to your questions (and the most accurate) are from your motherboard manual . .if you no longer have your manual then you can go to the ASUS website and download a new manual in PDF format. The manual will show you where your S/PDIF ports are; as far as the "second Line Out channel" goes . . it may be controlled by a software program or a jumper on your motherboard . . . but the manual will tell you exactly what software driver you need and / or the details of how to do it.
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