do I have to match the db level on all speakers?

I think the distance is one thing and the db rating of the speakers is a completly different thing. The distance alone will be sufficient only if all speakers are the same, otherwise I believe an adjustment has to be made in order to set all channels to the same db level (88db or 90 db).

I don't know about your receiver, but if available, the distances from each speaker should be measured and entered, for coherent sound. White (or pink) noise is greatly preferable to a tone for setting speaker levels. I think there are DVDs and/or CDs that have such noise, if your receiver doesn't generate it. The Radio Shack sound level meter is inexpensive and good, Use the C scale and slow setting. Hold the meter near your seating position, and a bit away from you so as not to create a major acoustic shadow. Set the output of all speakers equal. Don't forget the sub, if you have one.

db

You need to balance the speakers. This is a must. The speaker distance to center listening position is also very important. If the reciever is not setup correctly,you have wasted to money you spent on it.

Tim

Just run the test tone on your HT rcvr/processor and set it by ear.

I am pretty much on equal distances from each of the speakers (back speakers are closer to the listening position by aprox 2 feet). So I think ideally they all should be at 88db (or at 91db).

If all your speakers but one are at 88db, why not adjust the center -3db? Bear in mind that the acoustics of the room also enter the picture, as does the listening position relative to the speaker positions. You should adjust the speakers via the setup menu so the sound is right for you from your normal viewing/listening position -- the relative speaker efficiencies will then be handled as will all the other factors. Good luck.