I remember about 10 years ago my buddy had to use one of those channel out converters to be able to use his OEM headunit and it did the same thing. I admit I have no idea why it did this, but I borrow his car one time and just shut the car off and it did the same thing, just made a huge random noise. He said the speakers in his car continue to have power after the car is off. Either way, he added a basic toggle switch to his remote wire, and installed it in a coin hideaway storage under his steering wheel. I have since installed a toggle onto my remote wire just because it's a very convenient way to just turn off the system. As to whether or not it's healthy for your amp, I don't know. I've had the same amp now for 5 years with no issues. But if it was the only way I could use my system, I would try that.