Dear,
Is the ground port at the back of the RS130 possible to connect to a ground box? Thanks
It is possible to use it by connecting RS130 to the ground port and ground box, but it is not recommended.
It is recommended to use it by connecting the ground port of RS130 and DAC.
Sorry I don’t understand your meaning. You mean the ground port of the 130 isn’t supposed for the connection to a ground box?
Hello @Flash I am too green on that part… do you mean the RS130 shall act as the ground box of the DAC?
Sorry that if I mixed up between ground and ground box 
Thanks for your info☺️