Help choosing cost-effective motherboard

[Aurelian]

Hi! My upgrade shop list is getting done but seeking and choosing the motherboard still frustrates me. Could some more experienced folk give me some advise and suggestions? Also, is there any other reason to invest in a good motherboard than more slots that I would be unlikely to use - can a bad motherboard affect performance? I'm at the edge of my budget so I'm kinda hoping this wouldn't break my bank. But I also wouldn't want to break it later when needing to change it to clean up my mistake.

Wanted features and what you need to know:
- LGA1151 socket
- 4 RAM slots, support up to 32Gb
- USB3 slots (2 or more)
- At least 2 M.2 slots
- I'd like to use 3 monitors
- As a musician I have an external sound card / audio interface so I'd appreciate if as little as possible would be wasted on integrated audio
- I'm too new to this to trust myself enough so I'd appreciate if someone could confirm the compatibility of it with my hardware

HARDWARE
I'm upgrading to:
CPU: Intel Core i7-6700K or i7-7700K
RAM: 16GB G.Skill RipJaws VKB DDR4-3200 DIMM CL16
SSD: 256GB Samsung SM961 M.2 2280 PCIe 3.0 x4

I'll retain from my old build:
PSU: Corsair CX500 (500W)
GPU: 1024MB ATI AMD Radeon HD 5700 Series
HDD: 931GB Seagate ST1000DM003-1CH162 ATA Device (SATA)
OS: Windows 7 64-bit Home Premium

Thanks in advance!

 

[Calvin7]

You would likely want to use Z170 or Z270 Chipset motherboard.

Z170 may require a 6th Generation CPU to upgrade BIOS to 7th Generation CPU.
Z270 may not support your operating system with 7th Generation CPU.

MSI Gaming Z170A GAMING M7
https://www.newegg.com/Product/Product.aspx?Item=N82E16813130872

Motherboard has BIOS FLASHBACK+ which allows BIOS update without a CPU.

 

[jay_rogers]

I have used Z170 and Z270 motherboard but honestly, I found disappointment in Z270, it only really adds 4 more PCI-E Lanes. I think you should go for Z170.