SONY??? well, i never thought of them as being to high on the quality list, they used to be though. the reason why i chose sony was because it was all cheap cheap, and yes, its the dodgy versions. (ie, not made in japan), and not saying dont get them either.
another reason being my vit gets a lot of mud and water inside and stuff, so something cheap was the way to go. and it just so happens that sony got good prices. i got the speakers (2 sets of 6" and 6"x9"s for $190AUD and the head unit was $180AUD) and its MP3 too.
answer to ur Q? is the 6"x9"s pump, esp in the back with sealed and padded insides (refer to previous post) can't really say much about the 6"s though, pretty average.
if you want something to pump, and loud too, look into pioneer, if you want crystal clear sounds, go clarion, these are in the same market. you can step up a level, and go with the super dooper stuff, thats like rockford, kicker, polk audio etc etc, but now u'll be looking at big $$$. not practical i think.
anyway, just have a look around, and when they test the speakers in the shop on the sound board, don't believe that they'll sound same in your vit/car, its a marketing thing that they do. (they set up in store to sound the nicest, and some have hidden amps powering the speakers..... all to suck you in!)
have fun and good luck.
Steve