To avoid ground loops, power connections of all devices should be in a star connection and as short as possible, without obviously exceeding the power capacity of your socket. So, to get as close to this configuration as possible, it is better to connect all your devices to ONE power socket.
If however, your sub is wireless, this does not matter. I have mine at home wireless and therefore can plug it to any socket I want without any hum issues.
If however, your sub is wireless, this does not matter. I have mine at home wireless and therefore can plug it to any socket I want without any hum issues.