The audio module found on the X99A Tomahawk is very unique in that it features the Audio Boost 3 design and occupies a section of the motherboard that is electrically separated from the rest of the main PCB. You can see this separation in the PCB layers where the board is devoid of color.
To further illustrate that the layers are completely separate on the reverse side of the motherboard you'll find a series of white LEDs that light up and shine thru the PCB layers when the system is powered on.
The Audio Boost 3 design is powered by Nahimic Sound Technology and comes with a built-in headphone amplifier allowing you to get better quality sound from studio grade headgear which would normally require specialized sound cards.
One of the benefits to upgrading to a specialized motherboard is that not only do you get more features onboard but also in-box. The MSI X99A Tomahawk comes with a number of accessories including what you see below.
Unlike on some other MSI gaming motherboards the X99 Tomahawk only supports two physical cards in SLI so it makes sense that you would only get a single ribbon connector. Along with that you also get an RGB LED extension cable and high quality I/O shield.