i have a simple one for the audio folks. i have a 3.5MM cable ran to the inputs on the back of the radio in my car. i use this to play music off my phone. its not loud enough. the radio has a 0-40 volume range. regular radio i run at about 15-22. cds the same. DVDs are usually lower, 10-15 (there's a DVD player and a rear screen.) this is all in an 06 Honda odyssey, btw. but with my phone on max, and the volume on 40, its JUST enough to hear over normal highway noise. i need like 10 more ticks. so my question is this: is there a simple 12v amp that can go inline with dual RCA inputs to amplify the incoming signal a bit? i need like a 15% increase. i don't know what the max output of a galaxy s5 is, but that what im using. my wifes S4 is no better. buddies i-phone 5 is no better.