Hi, I have a 2000 Audi S4 with a symphony stereo, the right side speakers "pop", and at a medium volume, you can hear them buzz. I would like to have them replaced, but i might just replace all the speakers. I noticed that the rear speakers are clarion, but i don't know the brand of front speakers. Any tips on what brand to buy for the car? Also, are the front door speakers 4 inch, or 6 inch? Thanks