true, if you have the speaker level inputs then you can use that in place of the RCAs... but i guess thats only if youve only installed a sub. using the speaker level inputs wont make sense in my car, which ive amp'd up my front splits and my sub. if i upgraded my head unit (which i plan on doing eventually), i wouldnt be using any of the stock speaker wires at all. all my audio would be coming through my amps which is connected through the RCAs. i guess its depends on what your doing. since encounta is upgrading both speakers and subs, im guessing he wants to amp the lot. in that case he could do either the level inputs (if his amps have em) or the RCAs (+RCA adapter) since hes sticking with the stock head unit. but yea as i mentioned earlier, if hes got all that installed already and then decides he wants a new headunit, then hed have to use the RCAs.