SLC-4 question

[RobPaulson]

I have an Avic F700BT installed with the stock BOSE speaker setup. When I had it installed they used a SLC-4. During the install they tweeked the SLC to put more sound out of the rear speakers because i was complaining it sounded weak. This is a long story but i dont want to get into it, after everythings said and done i have my bose speakers and an aftermarket sub/amp setup.

Now just today i got around to trouble shooting a crackling sound coming from my front right speaker, so i isolated the sound to the front. I noticed instantly that almost NO sound is actually coming out of my front speakers. I have a feeling this is due to the 'tweeking' that the shop did when they initially installed everything.

SO my question is, how do i 'tweek' the SLC-4 to put more sound out of my front speakers so they actually get used haha?

Also, where is this SLC unit supposed to be located? I havent seen it yet since messing around behind the unit . . . so im a bit lost.