This has just recently started. I have had my amp and subs in for over 6 months. Now I get this interference type sound from the speakers. So annoying. Just a bad ground here or what??

 

That could be the problem. Check out this article from caraudio it has some very helpful info and solutions
http://www.caraudio.com/forum/showthread.php?t=198477

 

possibly a ground has become loose....also make sure you dont have any speaker wire running next to your power wire going to your sub amp. if you must cross speaker wire with power wire do it at a 90 degree angle with 2 zip ties.....

 

speaker wire can run next to power wire all day as your speaker wire dosent carry signal.

Its interconnects you need to worry about (and the concern is running next to wires for motors (seats, windows, etc).

Deffinatly upgrade your amp grounds and one most people miss, your stock headunit ground! the common ground used in your harness is pretty shitty. Upgrading this to a well known ground spot in your truck can do wonders for noise reduction.