I have no clue how some of you are implying that Media player has something to do with audio quality..
There are two important factors that affects sound quality: 1. Sound card; and 2. Sound card driver/OS and of course the speakers/headphones.
I have Audigy 2 and Inspire 5.1 back home. I got a audio DVD free with my sound card. It's really impossible to explain the sound quality of DVD audio. Its like HD movie vs DVD Rip.
Now, coming back to driver and OS, Mac and Linux produces better sound compared to Windows due to latency issue. But there are workarounds.. You can use ASIO drivers to bypass windows audio mixing kernel and directly connect to sound card..
If you want, try playing same track in Windows and Linux. You will notice the difference.