I ordered the Sonic Hub from Lowrance and it connects into the HDS network and can be controlled through both units. It comes with two 6.5" speakers and you can plug your Apple device or any other mp3 player into it. It also has Sirius Satellite radio and weather "radar."

If you use an Apple device it docks into a waterproof station that Phoenix will mount where your right elbow would go if you're driving the boat. They mount one of the speakers under the driver's console to the left of the Hot Foot. The other is mounded just above the passengers left elbow rest.