to go 7.1 or to stay 5.1

[xpatate]

I just got my new HD system. I have a THX 7.1 ready receiver with a 5.1 speaker setup : Polk audio RM6900.

Is it a good move to go to 7.1 or I will see no difference compare to my actual 5.1 setup ?

If I decide to go 7.1, I just have to buy 2 more satellite speakers (polk audio RM6801 in my case), put the speaker behing the listening position and that's it ?

[shokhead]

If its that easy,go for it but dont spend to much time looking for a 7.1DVD.

[Woochifer]

That entirely depends on your room arrangement. If your system sits inside a small to medium sized room with the sofa pushed against the backwall, forget about "7.1" and stick with properly positioning and optimizing your 5.1 setup (see diagram below). If you have a good amount of space behind the listening position, and you can position the back surround speakers at close to the same distance from the listening position as the main speakers with space to spare, then it's worth trying a 7.1 speaker setup.

Trying to shoehorn the back surround speakers into a room that's already barely adequate for a 5.1 setup will only detract from the sound quality. Keep in mind that fewer than 0.1% of the DVDs on the market have any kind of ES or EX back surround encoding present, so for the vast majority of soundtracks, 5.1 is the optimal setup.

http://www.axiomaudio.com/global/images/diagrams/dolby_digital_pro_logic2.jpg
Optimal 5.1 setup

http://www.axiomaudio.com/archives/images/dolby_pro_logic2x.jpg
Sorta optimal 7.1 setup (need to either setup the back surrounds equidistant to the listening position as the other speakers, or compensate for the distance by changing the delay timing)

[xpatate]

My seating position is at 14 foots on a 20 foots room so this is the ideal room for 7.1 if I understand correctly... I will probably give a try :D