Our hub adapters are BUS-powered and include active chipsets that will power themselves once connected to your computer. Yes, the adapters will get hot when plugged into the computer, even with nothing plugged into the adapter.
Our standard operating temperatures are 86-122° Fahrenheit (30-50° Celsius). Rest assured, this is normal and will not affect the functionality of the device, nor damage any hardware.
(Our only recommendation would be to use 1 bus-powered device at a time for optimum performance)