Yes, you must kill the mini jack. For < $30, this will be a vast improvement:
http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=248-599&CFID=2275801&CFTOKEN=21576422
Depending on your other components and/or DAC, you could also use the optical out, which might yield an even bigger improvement.
I use this type of set up for all my computers, both at home and in the office.
Moving up in price, you could try the Hagerman Technology interface box for about $150 (?)......
Finally, there seem to be more and more DACs which take a USB input directly.
Good luck,
http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=248-599&CFID=2275801&CFTOKEN=21576422
Depending on your other components and/or DAC, you could also use the optical out, which might yield an even bigger improvement.
I use this type of set up for all my computers, both at home and in the office.
Moving up in price, you could try the Hagerman Technology interface box for about $150 (?)......
Finally, there seem to be more and more DACs which take a USB input directly.
Good luck,