Hi Guys, i've got a Sony XAV-64bt Head Unit, and 6 inch Sony Xplod main speakers with a couple of Vibe 4inch tweeters up front, i used to run a 10 inch sub tube with built in amp and it all worked fine, ive now upgraded to a JBL GT5-A3001 mono sub amp and a JBL GT5-10 sub, now i struggle to hear...