It boosts the signal from my iPod that I have hooked directly to the amp. I am running a Vibe Litebox2 amp, Polk MM691 speakers and the PAC LD-10 in an icechest radio. I hooked the ipod directly to the amp with out the line driver and it was ok. I then hooked up the line driver and only had to turn it up 1/8 of the way. It made it sound like a dream. If you are going to hook an MP3 player to the amp with out a headunit I would suggest you get a linedriver. This one does not have any mounting screws or holes to use your own. I ended up using velcro to attach it to the inside of my cooler. It is a little flimsy but once you set it and find a way to mount it you shouldn't worry about that.