* Wiring: The biggest hurdle is the wiring. Aftermarket stereos often use different wiring harnesses than factory systems. You'll likely need a wiring harness adapter to connect the aftermarket head unit to the factory wiring, and that adapter may or may not include the correct connections for the Infinity speakers. You might need to splice wires yourself, which requires some electrical knowledge.
* Impedance: The impedance (resistance) of your factory Infinity speakers needs to match the output impedance of your new head unit. Mismatched impedance can lead to blown speakers or a weak, distorted sound. Check the specifications of both your speakers and your new stereo to ensure compatibility.
* Speaker connectors: The connectors on the back of your factory speakers might not match the connectors on the aftermarket head unit or the wiring harness. You might need to use speaker wire and connect them directly.
* Sound quality: Even if you get the wiring sorted, the sound quality might not be optimal. Aftermarket head units often have different power output characteristics than the factory unit, which might not be perfectly matched to the Infinity speakers.
In short: While you *can* try, it's often easier and more reliable to just replace the speakers with aftermarket speakers designed to work with aftermarket stereos. This ensures proper impedance matching and eliminates any wiring headaches. The cost difference between using the old speakers and buying new ones is usually minimal.
