Sure, you could but then you'll likely end up w/ a plug connection and two splices b/w amp and speakers. A better and cheaper solution would be to hit a radio shack and get a 4 position plug w/ connectors so you can cut wires to length as needed and not splice in a connector. such as:
That 4 conductor Molex is the way I went. I ran a new 6 conductor cable from my head unit to the rear, 4 wires for speakers and two additional wires for whatever future use
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