I did not realize when I ordered my 2010 smart that the smart 10 6 disk CD changer radio also had the "sound system" option untill i recieved the 2011 lightshine with the highline radio and cranked it up, then it was obvious that the sound was no where near the power that my 2010 had. so i did a little looking and found on the int.smart.com website under equipment lines an 18.88 MB pdf file on pages 84 and 85 that the term sound system is a speaker package option and not just a generic term for the car audio.
here are the definitions-
Sound system: compatible with all smart radios. Two tweeters, two mid-range speakers and a subwoofer.
Surround sound system: Subwoofer, 8-channel digital amplifier, tweeters, midrange speakers and rear-fill loudspeakers, Compatible with all smart radios.
I will attach scans of the 2 pages as they show speaker placment.
by looking at the diagrams it looks like on the oem smart sound system option the tweeters are in the dash, yet on the oem smart surround sound system there by the door mirror, had i know I had them before the insurance took my car I would have removed them and not needed to look for replacement.