hi, i want to know exactly what does that small box attached to the back of some HU's do. I know it's a DC-DC converter and has something to do with RCAs or some sht... how does it work? does a hu with it has improved SQ from it? i realized the best sq hus have it, even thou i noticed alpine 9815, for example, doesn't have it, while 9835 has.. that's weird, considering they should be the same hu after all
so... does it do something or what?