Beginner question about recording from a PC!

Hi!

My name is Mathias, I'm from Vienna, Austria, and I've got a question about recording music from a computer to a MD.

I've read that I don't have to set recording level if I'm recording from digital source with a TOSLINK cable.
Well, I've got a Guillemot MaxiSound Fortissimo Soundcard which has an "Optical Out", which means a TOSLINK Output Port if I understood this things correctly.

Now I tried to record a playlist from WinAmp to my portable MD-Player/Recorder, one of the expensive Sony models, and the result was extremely silent.

Now I was surprised, because I had thought that I wouldn't have to
set recording levels!
So I set the volume a bit louder in WinAmp and tried again. Now the first track was ok on the MD, but the second track,
a hard rock song, was much too loud and in a bad quality.
So I had to adjust recording level after each track. This can't be the sense of digital recording!

Could you please tell me what I have to do, when I just want to create a playlist and get it onto my MD, with no track too loud or too silent?
Is it possible that my soundcard is just not capable of
doing this? If so, I would buy a new one, but which?

I would very much appreciate if you could help me!

A merry christmas to all of you

Mathias