98 Jetta Factory Radio Problems

[VW98Jetta]

I own a 98 Jetta GL with the Premium factory radio. The other day I was trying to add a subwoofer, had all the wiring done with the sub working, until I go to drive my car a few minutes later and the Amp loses power. I have a feeling it's got to do with the remote power connected to the wire in the back of the factory radio. So I decided to take the wire out so it's just the Factory Radio running and not that and the amp. Now the radio stays on when I pull the key out when it initially turned off when the key was pulled. Anyone help me on how to fix this problem? I'd like the radio to be back to the way it was so I can pull the key out and the radio will shut off. Thanks

-G