We'll, heres the break down.

I'm going to be running Infinity Kappa Loud Speakers 4" in my dash(90 fc) and 6.5" Infinity Kappa 62.5i in my doors.

The specs on the speakers are
4" Kappa's are 50 watt rms, peak at 150 watts, frequence response(+-3dB) 75hz-21kHz, 4ohms
6.5" Kappa's are 75 watt rms, 25 watts, frequence response(+-3dB) 45Hz-21kHz.

I can't figure what kind of amp I should use or what should I do.

Option 1:
Run a 4 channel amp to power the door speakers and dash. Is that possible since the rms watts are so different in numbers?

Option 2:
Run a 2 channel amp to the 6.5" and run the indash 4" speakers to the head unit.
This is the cheaper method..

If I were to go with Option 1, what kind of amp should I look for to power all 4 of these speakers without under/over powering them. I'm trying to spend less than 200 bucks on the amp, but if need be ill go over a little bit. Anybody got recommendations?

I also plan on running two 12" Infinity Kappa Subs with a mono amp in the future.
I'm kind of new to the audio game, so I'm not too sure if its possible to 4 channel amp 2 sets of different speakers.

 

Well, I have a MTX 2-channel perfect for your application if you are interested. You could do the same method as on the SE.

 

you will probably blow your 4" speakers using an amp.

 

look at SPL, good mid-class kinda amp

 

Whats the specs on it?

 

MTX Thunder 4202. 280 Watts Dynamic Power Bridged into 4 Ohms
200 Watts RMS Bridged into 4 Ohms.
100 Watts RMS/CH x 2 into 2 Ohms.

I will trade you your scanner for it.

 

It is actually better to over power a speaker than under power it. If you take the wires directly from the head unit instead of the RCA cable (assuming it's an aftermarket unit), You can adjust the front to back on the head unit. A larger amplifier than the speaker means you will have cleaner power throughout the entire power band, especially the normal listening volumes . (Just don't crank the thing all the way). It's been in my experience that most all amplifiers are over rated unless you go well beyond the $200 range. An excellent amp for your money would be a clarion amp. I've had good experiences with SPL but have only used them on subwoofer applications. This model, the Clarion APA450 found here Clarion APA450
is a great one. I installed it in my friends WRX on inifinity kappas and it sounds awesome. Class A/B amps usually run in that range of price to $300 and sound the best IMO on high frequency applications.
-Eric

Edit- The current price is around 150 after shipping i believe.

 

Look at a 4 channel amp. I have a Clarion 50 x 4 powering the mids in my car, it's plenty loud and less than $200. The advantage to the 4 channel amp is you can use an active crossover on each channel, lessening the likelyhood of blowing your 4" speakers (they aren't going to make much of a difference). I myself ditched the small speakers in the kick panels of my 1st gen and put 6.5" component speakers in the doors and factory rear locations.

Thunderpup

 

Run a 4 channel amp 50 watts rms per channel, or up to 100 watts per channel. But make sure you buy a good amp such as JL Audio or phoenix gold ect ect ect.. Reason is they have good crossover capability, so you can match the amps to the speakers.

Are you running a good four channel output head unit, and amp?...they are the most important part of your sound system. Speaker grade and wattage are not as important as a good realiable power supply.

 

Hi Guys. Don't under estimate Infinity speakers. Even though they are 4" and 50Wrms they can handle being drivrn by an amp. I drive an '82 "7" fitted with a full Infinity Kappa Perfect system, and I've been in the industry for about 8 years. If you'd like to stick to infinity for the amp, try the 75Wrms x 4. You can turn down the gain and or freq on the fronts and the amp is big enough for the 6.5" Kappas in the back.

Infinity also has a Monoblock designed for the Kappa12. The Reference 610a. (which I have in my car). I don't have the specs with me, but its around 600 and sometning Wrms at 2 Ohm. Check out www.infinitysystems.com. I'd like to help where I can, if you'd like and trust my judgement.