If your Jeep has the premium sound system then yes, you WILL have an amp on the front door speakers. I am not sure if you can remove the amp and wire it to the new speakers or not.
The amp may also serve as a cross-over for the tweeters in the dash and if it does, you will need a set of component speakers+tweeters with a cross-over to split the highs and mids. If you want it to sound good you will also need a 4 channel amp to power the components and the speakers in the rear doors.
Main reason Ive not replaced my front speakers...

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Current Jeep: 2004 Jeep Liberty
-Atlantic Blue
-Air Ride Rear Suspension ; OME/Rustys Lift ; Powertrax Locker ; Moog Lower Ball-Joints ; 245/70/16 Yokohama Geolander A/T-S's on MOABS ; Flowmaster 50 SUV
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