I have a C280 '97 and I installed a Mp3 played they installer told me to get a reverse amplified antenna adapter and that he could not supply me with it! does anyone know where I can get ahold of this part to fix the sound because its is not sounding good and I cant get all the radio channels to work, but the installed said this part should fix it!!

its like s buzzing sounds like when you turn the volume to loud...

"Reverse Amplified antenna adapter"