Q1: "I accidentally cut the stock connector with out looking which wire went to positive and which went to negative, the wires are both identical in color and markings, there's nothing on the wires themselves to indicate polarity. I can connect the speaker either way and it seems to sound alright. I did however read if polarity on one speaker is reversed it would be out of phase with the others."
A1: That's strange that the wires are the same color. Usually one will have a stripe or some similar marking. Even if your speakers do get wired out of phase with each other you probably won't notice a difference. That is more of a problem when dealing with subwoofers.You won't damage your speakers by reversing the polarity. The music signal is an AC voltage so it really doesn't matter which wire you hook to positive. The voltage just causes the speaker to move in and out. The only concern with reversing polarity is the relationship to the other speakers (which is called phase). Again, it probably won't matter with your door speakers.
Q2: "What is the remote wire on a car amp for?"
A2: I've gotten several questions on this lately. The remote wire is what turns the amplifier on. There's a small switch inside the amplifier that is triggered by the remote wire. When you turn your deck on the remote wire sends +12 volts to the amplifier switch (remote terminal). This current turns the amp on. When you turn the deck off the remote wire no longer has +12volts and the amplifier turns off. This keeps your amplifier from always being on and draining your battery.
Q3: "I have a 4 channel, high-power receiver in my car (front left and right, rear left and right). I have no amp. What I am wanting to do is have my front left and front right channels power their respective speakers. However I would like to somehow "combine" my rear left and right channels into one channel to power a subwoofer. I don't want to short anything so I am wondering if you may know of a wiring scheme that would work for this purpose."
A3: That's an easy one. It can't be done. The amplifiers built into head units are not designed to be bridgeable. Even if they were your head unit still wouldn't have enough juice to properly power a subwoofer. Sorry to be the bearer of bad news. If you really want to run a sub off your head unit you could buy a dual voice coil sub and wire one channel to each coil (assuming 4 ohm coils). But again I wouldn't recommend that. You're much better off buying a small outboard amplifier with a built in low pass crossover.
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