The complete list of functions the 550 is capable of is quite extensive. If you look through this thread and the official 550 sponsor thread you will see where I kept apologizing because I missed so many of the things it could do
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Highlights I really are the ability to set a custom EQ I can use (its not super extensive but can be handy) plus the built in EQ's. The ability to be paired to 2 devices. The ability to use a smartphone enabled audio cable, the ability to use (and charge simultaneously) the USB cable with a computer for music plus headset (think apps like Skype). It really ticks off pretty much every box feature wise.