Firstly, congrats on the purchase.
Second, when you "doubled" the cable it would've only made a difference if it was raw cable since it would mean a higher stand count.See what's the difference between a 8 gauge and 4 gauge wire on Google.So basically the way you've wired your amp means it's two separate power wires hooked up to the amp and since current travels through the path with least resistance it will only pass through one cable making the other one useless.
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