ok i bought a 02 is300 a few months ago and was disappointed to find out that the cd player doesnt work. i wanted to buy a new head unit so i called best buy to ask about some stuff and was told in order to get a new head unit i would have to get 4 new speakers and an amp cause if i just get a head unit its gonna blow my speakers since its pre-amped. i wanted to know if i really have to get all of that stuff or if its just them trying to make more money off of me... cuz a whole new sound system is alot of money and right now. thats a lil too much for me to just listen to cds. XD
Normally I'd say look in the stickies, but since I hate stupid B&M (brick and mortar) idiots who tell you wrong information I'll just respond. No, you do not need 4 new speakers and an amp if you install an aftermarket deck. You have 2 simpler options
1) Buy a special harness for like $60-$100 to let your aftermarket deck use the stock amp and stock speakers. You aftermarket deck will need pre-outs for this to work though. This is probably the easiest way to go, but you will more than likely get better sound quality with option #2
EDIT: price breakdown for this option $xxx for headunit + $60-100 for harness + $10-$60 for dash kit
2) Use your aftermarket deck's amp to power the spearker, esentially bypassing the stock amp. In this case, you will need to replace only the rear speakers (not all 4 as the Best Buy fool told you). This is definitely more involved from a installation point of view, but it's not that much harder and like I said, you'll probably get better sound quality as long as the aftermarket HU has a decent amplifier built in it.
EDIT: price breakdown for this option $xxx for headunit + $60-$100 for 2 basic rear speakers + $10-$60 for dash kit
If you do what Best Buy says, it will no doubt sound better, but it will be even more difficult of an install than option #2 and they will make more money off you. I guess what it boils down to is how much you want to spend and how "good' you want it to sound. Check out the stickies for more details on the 2 options I mentioned.
EDIT: price breakdown for this option $xxx for headunit + $120-$200 for 4 basic speakers + $200-$xxx for amp + $10-$60 for dash kit + $50-$100 for wiring
p.s. It sounds like option #1 or #2 will suit your needs just fine if you "just listen to CDs"
p.p.s. forgot about one other option, buy a used stock hu from the forums. You should be able to get one for < $200, maybe even < $100 if you're lucky! This actually would be the easiest
