Audio Systems: no sound from speakers, ford wiring harness, blown fuses

Question
I have a 91 Ford Thunderbird LX with premium sound. The old stereo was only getting am radio channels so I replaced it with one from a 96 Lincoln which i got from a wreckers. My problem is that i am not getting anything from the speakers-nothing! The Lincoln stereo is an exact match for the Ford wiring harness and I do get power and all funtions associated with the power part of the stereo are working. I also got an aftermarket stereo(Pioneer) and installed it using a Pioneer to Ford aftermarket adapter. Again same problem. All power functions but no sound,not even a crackle or pop. There is an amp in the trunk .I have removed it to check for fuses but there are none and nothing appears to be burnt or broken. Are there easy ways to test the stereo,amp and speakers so I can find the problem. Any help you can give would be appreciated. Thank you  

Answer
Lawrence,

 you will need to by pass the amp .. when you have a factory amplified system in most all cases they wont work with any other head unit except the EXACT duplicate of the original.. to by pass the amp you will need to run new speaker wires to each speaker directly from your head units harness this will be must easier if you use the aftermarket stereo and adapter harness because you already have your splices there just disconnect the speaker connections from the adapter tape them up and connect the leds from the head units harness directly to the correct speaker right front + or left front - ect.. this should cure your problem but before wiring everything up check to make sure the speakers do function so there are no blown voice coils ect.. and also before you cut the factory amp out go to your fuse block and pull out each fuse one at a time and check ALL fuses not just the stereo related fuses and replace as needed if you have some blown fuses before you do a bypass try the system again .. hope this helps you out if you need anything else let me know

thanks