As with car stereos, each manufacturer incorporates different features and connectivity options in their audio control heads. For example, some companies, including Aquatic AV and Fusion, build audio control heads that accept a smartphone or MP3 player inside the stereo’s waterproof and shockproof chassis, thus protecting your expensive device. More recently, the conversation has shifted to controlling stereos through a multifunction display, a niche that Fusion currently dominates thanks to its now-industry-standard Fusion-Link. This software, which resides on an MFD’s operating system, uses an NMEA 2000, Ethernet or Wi-Fi connection to allow the MFD to control a Fusion stereo. And while Fusion is owned by Garmin, the Olathe, Kansas-based technology giant lets other MFD manufacturers — including B&G, Furuno and Raymarine — embed Fusion-Link software into their operating systems, thus allowing sailors of all stripes to use their MFD as a centralized jukebox. Manufacturers also commonly bundle wireless connectivity options, including Bluetooth, into their audio control heads, allowing users to pair their smartphones, tablets and PCs with their boat’s stereo system. Additionally, many stereo manufacturers still incorporate auxiliary ports in their audio control heads, enabling users to access their device’s music library via a simple cord, much like I did aboard Dark Star.