trouble installing amp

[dongsoo]

i have a 2001 x5 w/ dsp and i'm having trouble installing my amp
i got the power to work but i didn't get any sound when i tapped in. i'm using a hi/low converter and that has 3 sets of wire. 2 white, 2 grey, and a black one. i'm wondering if u stick the 2 whites together in the same connter 2 greys. or if u mix it or what. or if i don't use the hi low converter at all and just cut my rca wire and just use my rca wire