High level to rca converter

[gnevnev]

Hi guys. looking at putting the sub from my old car into my clio mk3 (update list).

im looking at getting a high level to rca converter thingy.
just notice that some of them have multiple wires leading into it. i know that four of them will be right -+ and left -+ but whats the other one for and do i need it?
btw the one im looking at is this: http://cgi.ebay.co.uk/Boss-Audio-Hi..._Cabling_ET&hash=item3f06bf38ae#ht_1497wt_905

cheers

 

[Dm_26]

It will be an earth wire AFAIK.

 

[gnevnev]

ah that would make sense, what would i connect it to? the earth wire for the hu?

 

[MT AUDIO]

seperate earth or youll create a ground loop