Add a RAID box to my PR4100

Hi
I just got my PR4100 24TB box and works good. Some transcoding for plex is a little slow but it is stable.

Now I am tearing down my old server and I want to be able to use the drives that I already have and add them to this box

Now I am looking to buy Mediasonic PRORAID 4 and install my 4 x 4TB drives in it

Now this box has esata and USB 3.0, how can I attach this to my PR4100, do I just run cable from USB to USB as this will be a permanent connection

Thanks