I installed my stereo in my '67 MGB GT, and everything on the "instalation checklist" has been checked. yet, I blow the fuse everytime I turn on the car.
Try changing the fuse to a bigger one, e.g. if you keep changing the fuse in your car and its a 5 amp, try a 20 amp, worked for me. Or you could install a sub and amp to take most of the power away.
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Try fixfault.com to fix in-car audio.