newbb

is RCA line converter necessary??
I have stock headunit... so I connected rca to my rear speaker..."MANUALLY"
just cut open the RCA wire... so I got 4 wires and wired up two wires to each speaker wire... isn't this what RCA line converter do???? no?
because when I did like that the sub was loud enough but it rattled little bit and kinda didn't go with the song...
so i was wondering... if i did wrong with RCA thing... or the problem is elsewhere

thanks..

one more question...
on the amp there were three control knobs... and one filter on/off button
what do level, low boost, filter level... knobs do?? and filter button???
when I turned them high the bass got louder...