PC Audio to 990 Best Way?

Hey guys, I have lost touch with the digital world and need some help. I finally have time with no more deployments around the world so I would like to get back into home theater again and eventualy catch up on things. I bought my Outlaw 990 back in 2005 and have not done any firmware updates.
I would like to know the best way to hook my new Dell XPS to my 990 for the best sound quality for all my music. Would it be thru the USB on the 990 or via a exteral DAC?
Thanks

What audio outputs are available on your XPS? If it has an optical out then I would go with that to get the best sound. The USB in to the 990 is also an excellent way to get the interface and can also be assigned to a channel if you want to watch movies off your PC. Adding another DAC to the stream isn't always going to result in a better signal.

yes it does have a mini optical in the headphone output. Is that a better way to go vice an external DAC?

I think you will like the optical input but the USB is also a good bet. You should try them before buying a DAC.

An external DAC will only help if its of higher quality than the DAC in the 990.
The USB connection is stereo only, whereas the optical connection will carry amulti-channel signal.