Hi EricA11, DI boxes are used to change an unbalanced signal to a balanced signal and vice versa, in your case no need for a DI box as 2 simple RCA male to XLR male cables is all you need……i used to use numark mixtrack and audio 2 dj soundcard connected to my PA speakers with no problems….i now use reloop terminal mix 4 connected to my PA speakers via 2 rca to xlr cables. You can find these cables at any decent pro audio shop……here is a link to them.
http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10244&cs_id=1024404&p_id=4776&seq=1&format=2
you can get these cables in various lengths….i just happened to post link to the 3ft ones.