How To get DTS/Dolby Digital output instead of PCM?

Hello
i am using "K-Lite_Codec_Pack_985_Full" WIth My Logitech Z906 Speakers Connected to my creative x-fi titanium champion With Optical Cable
when ever i play DTS or Dolby Digital Movies IN windows notification icon ffdshow always show input DTS output PCM 5.1
How To get DTS output?
is DTS is better then PCM?

PCM is how uncompressed audio is called. Audio always becomes PCM after decoding. It isn´t better or worse.

If you prefer that the X-Fi does the decoding instead of your computer, then you need to enable bitstreaming. Then the DTS will be outputted untouched to the X-Fi.
ffdshow audio decoder configuration > Output > Pass-through