Sometimes on audio components like that, you may need shielded wire to get rid of the hum. I have also had some luck with grounding the chassis of all your components, and that may help. Another thing to try (and this is a problem on these rigs) is make sure all you cable runs are straight, with no coiled wires. The guys that build these always like to give you a few extra feet coiled up somewhere.
2013 Voltage 3905