Audio Systems: Sound stops from speakers after Bose replacement

Question
I recently bought a 1999 GMC Jimmy SLT, and it still had the original stock Bose Premium sound system installed.  All of the speakers worked great, and the sound was excellent.  However, the head unit had seen better days; most of the knobs and buttons were physically missing, the CD player didn't work at all, and the few buttons that was still attached didn't work, either.  So, I replaced the head unit with an aftermarket receiver/cd player; nothing fancy and no frills-- just something that was supposed to be fully functional.

I used a Scosche connector (part #GMDA) and installed the new radio and dash kit with no problems, and everything worked as it was supposed to.  That was 4 days ago...

Two days later, ALL sound stopped coming from the speakers while in operation.  The new head unit was still transmitting and was working as it should.  I checked all of the fuses (which were all still good) and completely rewired the connector adapter/harness thinking there was an exposed wire somewhere causing the audio loss.  When the work was done again, I had the same results--  a fully functioning radio and no sound.

After doing some research on my own, I tried connecting a Scosche converter/amplifier interface (part #FAI-A), using "Illustration C" as my guide. I double, and triple checked all of the connections and they were all correct.  When I tested the new installation, I still had the same results--  a fully functioning head unit, and no sound in the speakers.

Where should I look in the system to try troubleshooting? What could be another explanation?  How do I troubleshoot this issue further?  Any advice, help, and/or direction in this matter is greatly appreciated.

Answer
your factory BOSE stereo  comes with a 1/2 wat per channel, the amplifiers are behind the speakers, yuor new high power radio is 40wx4 to much power for the amplifiers

you install the speaker level interface a little to late

check all the fuses, if they are ok its possible that you birn the amplifier,
just remove it and connec the speaker to the new radio