I am looking to upgrade my HU to a double-din 7" touchscreen, and I am looking to see if anyone knows a bit about the Shaker 500 system. Is the Amp internal in the shaker unit? Or is it external and able to be used with an aftermarket HU? Also, can the stock speakers be used w/o a problem with aftermarket HU until I upgrade them? I thought I heard that the Shaker system doesn't like to play well with others =\... Anyway, that's the road I want to travel down... any advice is appreciated. Thanks all!!!