I need a tone control. A simple thumb wheel to vary bass to treble would suffice. I am running a cheap MP3 player direct into an amplifier, the to speakers. Can't fool around changing the equalizer setting on the MP3 player while driving, so need a simple tone control. I have searched the net and found nothing. Next step would be a small equalizer, say 3 channel. Where does it fit in, before or after the amp? Does a small equalizer need it's own power separate from the amp?