I have my amp grounded to the battery and I have very irretating "hissing". Or something like that! It doesn't even matter if the bike is running, radio on/off. Just turn on the ignition and and there it is. A little hum/hiss. It's really driving me crazy!
Have mine on forks.......all last summer 12,000 miles, highs of 106deg and clear and loud......perfectly happy......I am talking about the 300by2 not the 4ch.......