That card has a few inputs. Get yourself a recording software. Connect your hi-fi using an analog output to the CD/Aux input on the card or use the SPDIF output on your hi-fi to feed your SPDIF input on the card.
There are cards out there better suited for recording. Your card is primarily an output card... made for playback of audio. It can record audio though. You just need to find a recording software. Then tell your software to use the Asus card as the primary recording device. You may have to do that in Windows Control Panel/Sounds also.