Assuming you mean Abletons Live software, it does use hyper threading but its multicore use is a bit confusing. It seems to assign individual tracks to single core usage, so presumably the faster the core speeds the better, but I'm not 100% on that. Here is a quick blurb from their FAQ
https://help.ableton.com/hc/en-us/articles/209067649-High-CPU-load-on-one-core-when-using-multi-core-machines
Reason software is multicore and hyperthreading friendly. So an i7 would be of great use for both software sets. And since you're not gaming, you can get by with the integrated graphics on the i7.
The CPU you have in mind would be great for the software you want to use. And since you're going with a k series CPU and Z series board you can always overclock.
Real quick on your proposed build, there are two changes I'd make off hand:
RAM - Change out to DDR4-3000. It's cheaper and has better performance
http://pcpartpicker.com/product/LhgPxr/gskill-memory-f43000c15d16gvrb
CPU Cooler: If you get the K series chip, you'll need to buy a cooler for it. I don't know what your case is, but if it has at least 145mm headroom for a CPU cooler I'd go with a Cryorig H7. Good all around cooling and you can get a good overclock out of it.
http://pcpartpicker.com/product/93Crxr/cryorig-cpu-cooler-h7
PSU: It's going to depend on your country, and since you use the term cabinet instead of case I'm guessing you're not in the USA. If you can, the EVGA G2 series is in general a great series, but I know availability can different depending on your country. A good 550w is not only fine for your system build, its actually more than you need. But it allows you the option of expanding your hardware without much concern. If you list off the vendors you're using we can see what kind of good PSU's can be recommended.
One last thing, the Asus Z170-A has some good reviews all around. But it has a slightly lower end onboard audio chipsets, the Realtek ALC892. For normal use, its fine for most people, but since you're doing audio work you might want to look in to it a bit deeper. The Asus Z170 Pro Gaming, while obviously marketed towards gaming, uses a their Supreme Audio (they're rebranding of the Realtek ALC1150) which may make a difference in your work. Not sure as I don't do audio work, but just something to think on. Of course if you're using 3rd party audio hardware already, disregard this entire paragraph.