The following free advice is only that..and as you've probably heard, opinions are like rectal apertures...everbody has one.

I can happily spend your money but in a practical situation, you might look at the i7700k.  There is a difference in cost but futureproofing has some merit. My last 5 computers had a running life of about 6 yrs each ( yes, my first was an IBM XT with a 10mb Corvus hard drive) before seemingly bogging down by improvements elsewhere.  I am currently using the ASUS TUF Z270 Mark 1 and it is a great motherboard. The construction is terrificly solid.

One nice option that I know little about is the Optane Memory Module that will be here in a few days.  Reports say it will store and load your most used program overhead very quickly....for what I've put into this new build the extra $40 is minimal and the results appear to be quite promising. Whether or not it has a place in our application remains to be seen but it seems to really do well. The m.2 slot is on the ASUS board.

You can always add another 8gb strip of ram if your daw demands it. My biggest problem with boot drives under 256gb is that they get loaded up with updates, adobe, other drivers and "stuff" and there is a point when it tells me there is not enough room on the drive to perform some task and it stops any update in its tracks.

My choice with the z270 I have is that I wanted Thunderbolt...don't fully need it, but it's out there and I want to try things these days that I was unable do to in prior years.  If I can recommend a case...look into the Nanoxia Deep Silence series.  They are quite heavy by other standards but I have not seen a case so well built, solid and AMAZINGLY quiet. If you use a water pump with radiators, the ASUS board needs the larger case or the radiator infringes on the edge of the mobo.

Most importantly,  there are guys here with extreme knowledge of these things so my findings come only from trial and error over the last 34 years.  I'll say that I am very happy with the performance of my newest computer build over my 6yr old 2600k. The variables in the bios allow for some detailed setups.  There has been 2 updates already there.  This water pump cooler and two built in fans keep this running under  25° C and the fans spin under 500rpm so they are quiet quiet!

Hope some of this helps

EDIT: I am reading that FireWire I'd likely obsoleted...FYI

Don't go for a reduced chipset. Use the more powerful Z variant even if you do not overclock.

Dont overclock. More wear on components and likelyness for less stability. Also produces more heat.

When selecting the CPU look for the base clock, as you wont reach turbo frequency. For reduced latency for processing programs you will optimize BIOS and OS settings which prevent core parking and energy saving so that you will eventually get permanently approx 100MHZ above base clock permanently but not more.
Good is to get a CPU with at least approx 3.5 GHZ base clock so that you have enough single thread performance.
Use a CPU with hyperthreading, with most applications you get a performance win.

6-core CPUs are nice.

If you plan to do do video editing then I would go for 2011-3 boards with double mem bandwidth.

I would not rely on internal GPU. It uses memory from your usual DRAM and esp on laptops the builtin GPU leads to clicks and pops even when using asio driver for audio playback. I regard these solutions as cheap to to save costs and IMHO CPU and GPU should use their own memory not to block each other when accessing RAM.

Rather than taking any internal GPU or old passive card I would go for nVidia card with zero fan feature. Either Maxwell or current GPU family. Even if it costs 150 on top. Some video editing SW can even make good use of GPU power if available. The fans wont blow under 60°C and this you wont reach with nowadays nVidia Chips with Office or Cubase.

Take a mainboard that offers also ×4 lane sockets for high performance add on cards. If you use the x16 sockets of graphic cards then its possible to impact your graphic card to run with x8 instead with x16 lanes. Sometimes sockets are sharing lanes with other components on board. You should check this upfront in the handbook of your mainboard.

If you take SSD, and you should do, then calculate that you need to leave free 15% of netto capacity to ensure long and sustained read and write performance. Taking the bigger SSDs ie 512 instead of 256GB has besides capacity the advantage of higher I/O bandwidth.

For Ultra performance take M.2 based SSDs and/or even split Os/Programs, Sample Libraries and User Data between 3 different SSDs or a combination of SSDs and Harddisks to have multiple times the Sata bandwidth available. IMHO cheap and solid is a combination of 512GB SSD and 1-2 TB 7200 U/min Harddisk for user data and on top 3-4 TB harddisk for backup.

Best add NAS to have also backup external from PC. Cheap solution is to use Sata 6 hot swap case in PC to make weekly backups and after backup you eject disk take out of pc and store in another room.

A reliable backup solution is Macrium reflect for doing disk images. User data / projects I also mirror to backup drive to have data accessible in native format shall backup sw have issues to read data.

Shall usb performance have issues as all bad things can happen if you use different USB devices, then you can use an USB3 controller with from RME tested Fresco chipset. I use successfully the model which has 4 USB controller mounted, one for each of the four ports.

Now that is a detailed reply...!

With regard to water cooling...it is a very simple sealed system that mounts onto the CPU and has a loop going to the radiator.  I've had to think about it twice in 7 years. Once when I installed it on the 2600k and once when I ordered a new one for this i7700k.  If you see it in your future plans, don't let anything else intimidate you....there is nothing to it

Very good point Ramses makes with the video card versus on board graphics.

Good luck.

If you get a board with thunderbolt 2 then you dont need an additional adapter to connect a recording interface like UFX+.

Don't be frightened to get a graphic card.
I used MSI GTX 970 and now Gtx 980 in my silent PC build. Even when gaming it reaches merely 54°C so that all blowers on this card are always off. Its the 4g gaming model. Now newer cards are out with more power. Take one of the smaller models not or not so overclocked.