Great replies, especially ColonelForbin! My dream rig (jtv69, hd500x, dt25 head, dt 1x12 cab) will arrive on Monday and I'm going to use his reply as a quick start guide. I also ordered a 3' 16 gauge speaker cable (head to cab), a 25' AES/EBU cable for L6 Link (hd500x to DT25) and a VDI cable for the Variax.
I own a Variax 500 and Vetta II so I also ordered a couple extra speaker cables to try some funky experiments.