1. Make sure the TV audio is set to SURROUND (the AUDIO button on the remote control). If it is set to stereo, you get less. Use STEREO only on stereo only programs, use SURROUND for surround progams
2. Make sure you Directv box is set to send Dolby Digital on the HDMI cable. If the box is sending only PCM (Dolby off) - that is stereo not surround sound.
3. Yes run the mic or manually setup the sound projector (room size, TV placement and channel levels) via the sound projector menu. You may want to pump up the center channel level. Note: if you use the mic, then you do not use the custom because that cancels the mic.
4. A sub-woofer would help.
If you are using the out of the box settings, there is a very small chance it is proper for your room at out of the box default. Your room's accostics have a huge influnce on all audio systems and the defaults for any system normally do not work.