? Converts the speaker levels of a factory or aftermarket radio to RCA while giving the user remote control over the amp volume;? Allows user to add a trunk-mounted amp ;for subwoofers;? Provides an additional set of preamp outputs from a head unit equipped with only 1 set;? Allows more control over a systems sound;? Adjusts head-unit output from 2W-40W per channel ;? Mounts in dash or under dash;