DAC-80 is designed to remove hum and buzz created by ground loops.
Normal voltage differences in the system grounding points between different pieces of equipment cause small AC power currents to flow in the shield of audio cables.
Capacitance between a power transformer's primary and secondary windings introduce signals to the circuit ground which will also create small current flows in the cable shield.
Either of these problems will create hum in audio signals. DAC-80 breaks the interequipment ground path and greatly increases the rejection in the input circuits while remaining transparent to the audio signal.
Conferences, huddle rooms and presentations are fast paced environments where time is money and the audience does not like to wait. This is where an AV converter like the DAC-75T just thrives. Your speaker wants to connect their laptop and see it displayed or projected straight away. They may have VGA, DVI, HDMI, Display Port or even SDI. So not getting the picture and fiddling with tiny dip switches, in a dark room, is what they want to avoid. Especially when there is no tech guy around.