Sound Quality, so so ???

Ok just evaluating the new rekordbox dj software

Does anyone know why when using the PC sound card the audio quality sounds so dull and muffled ?

I'm not saying the sound card is the best in my I7 PC and I'm think of buying a RME external high end sound card to process all my music BUT....

But when I play my lossless music files through a range of windows music players they quality sounds bright, crisp and clean. Not what I'm hearing in Rekordbox 4 ???

Rekordbox sounds dull and muffled in comparison.

I understand also that I have not connected up my SX2 controller and played the files through that either.

But why should there be any difference to what I am hearing in the windows media players to rekordbox ??

The is no additional eq added to my windows players so surly rekord box should sound the same, but it doesn't, it sound lacking in so many ways.

Oh I am play flac files, maybe it's that it can't decode flac files very well

All I know is so far the audio playback quality from rekord box is disappointing.

Any help would be appreciated

Thank you