What configuration do you plan on running your SSDs? As this is a productivity workstation, I'd recommend getting an APS battery backup as well if you don't already own one as sudden power losses and SSDs don't mix well. I would go with the unlocked series, especially if you're going to have the Z board. You might not overclock now, but it'll give you room down the road. Since this sounds like a work computer, it also could allow you to undervolt which would save you on the electric bill which could help in the long run. I haven't seen too much on undervolting the skylake series, but I'm sure with how much headroom they have it can be done.
All in one watercooling is great. Definitely do not shy away from it. Like gilbadon said, they're easier than air. Just try to orient them as an exhaust and not an intake. For sound editing, I don't think you need to deviate from where you've gone so far, especially with wanting to future proof.
Going back to the SSDs for a minute, you might want to consider a backup data drive like a 2-6tb hard drive to dump stuff onto if you don't have a NAS system or some other config already set up. Extra redundancy never hurts.
I have two Intel 750 in RAID 0right now and it's incredible, definitely would recommend it if possible, especially for editing.