Several ways, depending on your computer outputs:
USB Port>USB Cable>USB DAC>RCA Cable>Pre
SoundCard Digital Out>Digital Coax Cable>DAC>RCA Cable>Pre
SoundCard RCA Out>RCA Cable>Pre
Soundcard mini-jack out>mini-jack to RCA Cable>Pre
USB Port>USB Cable>USB DAC>RCA Cable>Pre
SoundCard Digital Out>Digital Coax Cable>DAC>RCA Cable>Pre
SoundCard RCA Out>RCA Cable>Pre
Soundcard mini-jack out>mini-jack to RCA Cable>Pre