93' XLT premium sound system radio

[radiohead]

I am rolling with the stock radio/cassette deck in my '93 ford explorer. As time has progressed, more and more of the buttons have stopped working. First preset buttons, then the volume control and finally the eject button has become unresponsive. Since I switch between ipod and radio this was the final straw. I have decided to either fix the radio I have or replace it with a new one or one form a salvage yard. I removed the radio and removed the antenna plug and the long rectangular one. However, I could not remove the one with the thick grey cable. Seeing as I did not want to cut it (it would obviously be a pain to rewire judging by the number of cables inside it) how do you unhook this cable without damaging it?
Any help would be appreciated.

 

[radiohead]

I fixed my first problem. My new question is the replacement stereo. The deck I am looking at is a Kenwood with a built in 50 watt amplifier. Since I already have an amplifier in the car (it is the premium sound system) is there a risk of blowing the subwoofer (or other speakers for that matter) by having it run through two amplifiers?