Final answer:
Self-powered hubs should provide 500 mA per port as per USB 2.0 standards, ensuring adequate power for connected devices.
Step-by-step explanation:
Self-powered hubs that provide 500 mA per port are recommended to ensure an adequate power supply to all bus-powered devices that you may want to connect to the hub. This specification aligns with USB 2.0 standards, which require that up to 500 mA be supplied to ensure proper operation of peripheral devices. Furthermore, this would appear to be a sufficient amount of power, especially for small appliances or devices that do not demand high levels of electrical current.