Digital signal to preamp

I have read many threads on this forum, but I am still unsure of the best way to get a digital signal from my PC to a preamp. I want to be send lossless music files over a digital cable that is connected to a preamp. I just want the PC to send a pure signal (bit for bit) of the lossless music file to the preamp and then let the preamp do the DAC. I have read reviews of sound cards and some say that one sound card sounds better than another, but how is that if all of those sound cards send out a digital signal?

On another note, is there a preferred music player to send a pure digital signal in Linux?

Are you asking what kind of cable to use? Like what is better optical or coaxial? If that is the case, only page on the web that was remotely helpful to me was this one:

I have a Macbook w/an Airport Express and needed an optical cable with a mini-toslink. I ordered the VanDen Hul but haven't received it yet. No help if it makes a difference.

I don't know anything about sound cards. The only thing that would affect sound with computers/digital signals/audio might be the controversy surrounding "jitter". You're probably familiar with this discussion. If not, look in the PC Audio forum.

Hope this helps.

By the way, I've found that AIFF and WAV sound better than lossless. Lots more memory though, but found that 320kbps to be at least as good as lossless (might even be better, for some reason). Although it must be noted that my system is not super resolving or anything.