Wait, so you do have DSP or no? If you do, there is your reason for no sound, USA Spec includes an extra cable for the DSP as far as I remember, its not going to work right if you just use 6 pin cable and don't hook anything up to the amp

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2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards