This is just one use for the DC-125. With its included ports (audio, VGA, USB downstream x2), a user could also employ it to connect their speakers, computer monitor display, and peripherals (mouse, keyboard) with just one USB port. Another use is to add three additional monitors (one VGA, two USB) to a single computer. For normal usage, no power adapter is required. If however a high power consuming device is connecting to one of the downstream ports, then an AC adapter must be used.