IN response to Mr Basmith's posting on proper placement for your S30's, this is as far as 99.9% off the people ever see for good sound from their speakers!
I don't care if the manufacturer likes to see their speakres 20 degrees behind and almost 6 feet off the ground! Using that as a hard and fast rule is still going to garantee that you'll end up with likely poor sound from the speakers!!!
Now grated the main action is still happening in the front speakers, but it still matters!
I'll state again...EVERY ROOM/SET-UP calls for different speaker placement!...especially if your not using EQ's to help balance the speakers properly!!
Different places on the wall will have dramaticly different changes to the sound you get from a given speaker! If you are putting those speakers on the wall where the manual SUGGESTS you put them, you might just find that there's a huge hole at critical bass frequencies, or large lumps at uperbass/lower midrange frequencies, and get cruddy sound that either sounds week dynamically, or boomy, or lumpy, or at least tonally completely different perception wise than the mains!
I simply cannot understand the logic behind placing speakers "just so", so they are in the possitions you "think" they should go, yet end up with A BAD SOUNDING, POORLY BALANCED, UNATURAL SOUNDING, INCOHERENT, "NON FLAT RESPONDING" SPEAKER, THAT YOU MIGHT AS WELL JUST BUY SOME OTHER CHEAPER SPEAKER AT THAT POINT AND BE DONE WITH IT!...saving money in the process!!! Because that's exactly what's going to be the case, no matter how much you spent on the speakers, or pottentially how good they are capable of sounding, if you don't know how to make em sound good in the first place!..and every room sound different in different locations!...every room!...it's the law of physics your dealing with here....impossible to overcome or fight against it with out serious trade offs.
I'll say again, lOCATION, LOCATION, LOCATION, is the single biggest factor in getting ANY speaker to sounding good in relation to your seating area!
...there are much MUCH better ways to figure best speaker placements in the room, and it doesn't simply involve someone's "suggestion" as to where they should go in "blanket" statement! Yes, you can try to keep them in general areas for perspective and locational cues for sure(infact you need to get em in a general area of target if you can for sure). But your speaker locations varying from just inches to feet in one dirrection or height to another, will great impact the sound!
Good luck...there's no formula answer to where to put a speaker in any room! You gotta know it's different from circumstance to circumstance.
Good luck