You don't need to upgrade you just need something with a softer tweeter. I have the same speakers in the rear accept mine are 6.5's I find that they have unusually harshe tweeters and don't forget that they are 2ohm speakers so they will always see more power than 4 ohm speakers which your fronts are if i remember correctly. Could also explain the aggressive shrill noises at high volumes(mine do the same i've solved it by turning the gains almost all the way down).

 

Do the 6.5 have these special magnet too ?? With the amp that I got JL 450/4 the Impedance don't affect the output so it gives exactly what it's written. For now they got about 1/3 of 150 w and they are at the limit of screaming too much for me at high volume. So it's why I want to upgrade them I don't want to hear this anymore.
Do Hertz, Arc audio, Focal, Rainbow, Morel, Mb Quart, Boston Acoustic, Dynaudio,... Can any of the brand have some model that can outperform or be as good as CDT ES serie?
Am I right to have high end model to fill my rear stage or should I simply go with something a bit better than those infinity ?

 

It will be pretty much impossible to outperform CDT ES-610 for $340 through Ross. There are plenty speakers that can potentially sound better to an individual, but not in this price range. If money is no object, let us know. The only other option I can think of is Diamond Audio HEX on Ebay. They have a few sets for less than $200 plus shipping and duties. That is really the best deal out there, cause the Diamonds retailed around $1000 at one point. Either set will be incredible on your front stage. In this case, I would rather you got Diamond coaxial as well for rears. I believe you have a choice between silk or aluminum tweeter. I would pick silk all around. And please switch 150w back to the front.

And to answer your question about power for front vs rear, JL already answered than question for you. There is a good reason why they gave you half the power for the rear. You have one amazing amp, and time to use it properly and to power nice gear, just drop the entire Kappa line, if you're not fully happy. CDT and Diamonds will blow those things out of the water. I had Kappa in like 2002 I think, and now I have CDT, not the other way around.

 

another option may be the mb quart. I have those in my front stage and they definitly sound better than my infinities. I actually don't like my infinities, just too cheap to replace them. You should be able to find them for that price point as well. Sasha is right you don't need any where near the power in the rear that is needed for the front.

 

I also want to know how good focal is ?? everybody talks about them as they were god, do they really worth there price ?? Is it only the Utopia model that is incredible or avery model are good ?? Can they be compare to other brand such as CDT ?

 

I don't run rear speaker. instead of spending money on rear speakers, put it towards fronts, a good set of fronts and your good to go.

 

Have you put this into your sunfire ?? if yes, well, I got a 4 door toyota corolla 2003, it`s a bit bigger than yours and I don`t think people on back seats will like the sound, no ? It`s why I think I will need a rear stage. Does it sound good even for your back seat passengers ?

 

Rear fill, 6 x 9's and SQ don't usually go in the same sentence. It makes it really difficult to tune your ride with rear fill that it doesn't really seem worth it. On top of that you want to use a shape that isn't pure.

It's my opinion that if you're going to use them to appease rear passengers, then turn them off for competitions. Spend your money on the front stage.

 

Focal is excellent, but cost more, and do not have anything good in your price range. IMO, it only starts to get good with K2P's and up. New K2P's will cost you at least double your budget. Mb Quarz also starts to sound good at MBQ and higher. Boston Acoustics Pro or higher, Arc 6000 but not lower, Hertz High Energy or higher. Dynaudio or Morel do not sound good unless you spend more money. Diamond Audio Hex blow everything out of the water for being sold for under $200 on Ebay right now. IMO, for the price you can get Diamonds and CDT right now, nothing will touch them. It is very convenient, you can get coaxials from Ebay for rear fill. Diamond Audio is available, and CDT through Ross. So with whichever brand you choose, you can also get rear fill speakers from the same brand to match up nicely. I see Diamonds are as low as $59 for a set. Just make sure the tweeters on both sets for front and rear are made of the same material - aluminum or silk, but they have to be the same.

You may run rear fill, and fade them out with head unit fader, so you don't even hear them from the driver seat, but only sense the ambience. With this setting your passengers in the back will also be happy. If not happy enough, you can always fade them back in just for your picky passengers, and then you can fade them out again to the original state when they are gone.

 

Diamond Hex component are they in the same categorie as CDT ES serie ?? or Am I better to pay a bit more to have some CDT ?