H22accordR

So a few days ago i ended up trading my Sony cdx-m610 for a Pioneer Deh-6500, i am very pleased with the difference it made overall espically all the eq options which my subs really seem to enjoy. The deck is like a month old and i was with him when he bought it from best buy but he came across a deh-7500 for a good price ($40) so i was glad to take it off his hands.
The only thing i dont like is when i turn it on theres a crackle from my back left speaker for just a split second but i dont think that noise is normal. i have already ran good 14 guage wire for all the speakers from the deck back so i dont think a short is possible. I re-installed it with insulated crimp terminals and heat shrinks and insulated connectors on the speaker (lightning audio 6x9" 3 ways) so i dont think its a connection problem.
Does anyone with this head unit have this problem or is it me??
btw: on the speaker outputs (gray,white,green,purple) the wire with the black line is negative right?