I currently have all four of my devices plugged into my motherboard, and the D5 NEXT has its SATA port connected to the PSU. I don't think the Leakshield draws power from that SATA port, right? If that's the case, then I should just need to adjust the BIOS settings like Speedy-VI mentioned.
The Leakshield (LKS) is powered by its USB port. It has nothing to do with the SATA power connection to the D5 Next. If you decide to get a Hubby7, I would power it with SATA but plug the LKS USB cable directly into one of your mobo USB2.0 headers, which you should be able to configure in the BIOS to remain powered when the computer is shut down. This way the Hubby7 can deliver 1000ma max to whatever is plugged into it and the LKS gets its power directly from the mobo USB2.0 header that remains powered when the computer is shut down. The Hubby7 manual says when SATA powered, it can provide 500ma total for ports 1, 2, and 3 (combined) and 500ma for ports 4, 5, 6, and 7 (combined). Keep that in mind when you decide which ports to plug things into. The LKS can pull up to 500ma which is the max a typical USB2.0 port can provide. IMHO, it's best to power the LKS directly from the mobo.
If you set a mobo USB2.0 port to remain powered, plug the Hubby7 into that USB header, set the switch to USB power, and then plug the LKS into a port on the Hubby7, it will pull the total amount of current that the USB port and the Hubby7 can deliver when powered by USB. You could not use any of the other ports on the Hubby7 which defeats its purpose. If you powered the Hubby7 with SATA and plugged the LKS into Hubby7 USB port 1, you could not use ports 2 and 3. If you plugged the LKS into Hubby7 USB port 4, you could not use ports 5, 6, and 7. And the LKS will lose power when the computer is shutdown. It just makes more sense to power the LKS directly from the mobo, and power the Hubby7 with SATA power so you can have the full 1000ma available to the devices plugged into it.