Huge radio F-up 2001 Gt..Help

[Zaner]

2001 Mustang GT, Mach 460 stereo system. My car is a convertible and when I bought it the head unit still lit up but no sound when play because the rear amplifiers were not functional in the trunk. So I replaced the head unit with an aftermarket one and I replaced all of the 8 ohm speakers with aftermarket 4 ohm speakers and ran the new speaker wires to each it all looked and sounded great until I decided to do some cleanup. I took my back seats out and removed the amplifiers from the trunk since they didn't work to begin with. And I also cut the amplifier harnesses that plugged into each amp.thinking in my mind I'm not using them anymore so why have the wiring in the and amps back there. As soon as I cut the 2:00 amplifier harnesses off my radio will no longer come on. I've looked at all the fuses under the dash and under the hood and they all seem to be in good shape. What have I done! Have I somehow cause an incomplete circuit or something not allowing power to get to my head unit? Or the harness is going to the amplifiers even though they weren't functional more important than I thought?