As the title suggests, I've had a large pop coming from the relay on the left driver kick panel for some time as well as a coming and going high pitched whine in my 1990 Maxima. The rear left speaker has also quit working. I think most of these problems are due to the Bose amps, but I'm not sure. What's the cheapest way to replace the relay and the bose amp(s)?

 

loose ground