Sony BDP-300 and PCM

[Man-Is-Obsolete]

My setup is as follows: Sony BDP-300 to Yamaha Rx-v661 to Sony KDS 50a2000, all connected via HDMI. Speakers are Klipsch Quintet III with a Polk sub.

When watching movies I don't notice a big difference between PCM tracks and dolby digital. I was told there is a night and day difference, but i am not hearing it. Is there some settings I should change on the player and or receiver to fully get the experience. On the player's audio settings there is an option to do auto or pcm. I have it on auto because that will bitstream DD and DTS which the reciever can decode and still send, at least i think, PCM.

Thanks for any help.