para nako based sa ako na experience, bati ang sound quality sa FM transmitters because of course its only FM signal, daghan static and its very hard to find a very clear unused frequency esp in the city labi na diri cebu na pirti nang daghana radio stations. sometimes its either static or gamay interference from the nearest radio station. as much as possible kung naay AUX input imong stereo or kanang mga high end na naay ipod or usb input, plug it in and dont bother with FM transmitters, layo ra kaug difference in terms of sound quality. pero if walay AUX o walay lain option, FM transmitters is a godd way to listen to your mp3 players without needing to burn and re-burn your songs into cd or listen to bad radio stations with lots of useless commercials
in terms of sound quality:
CD > AUX/Ipod/USB input > Cassete interface > FM Transmitters