Are your fuses the right amp rating for the amplifier (example: running a 20A fuse on an amp that requires a 40A fuse)
You may also have a short somewhere along the line in your power cable. does the stereo work with the car in the accesory position, or does it just pop the fuse whenever the amplifier is turned on? If you are running your power line and RCAs down the same side of the car it's possible you may have damaged the wire and it's contacting metal (grounding out) which would pop the fuse. Also make sure the wire to the amplifier is hooked up correctly. I know you said you only changed the RCAs but it's always worth looking into unexpected explanations.
