This would work perfectly fine then, great even, for what you want to do, and just about anything else you would care to take on as well.
PCPartPicker part list /
Price breakdown by merchant
CPU: Intel Core i5-6500 3.2GHz Quad-Core Processor ($199.89 @ OutletPC)
Motherboard: Asus B150I PRO GAMING/WIFI/AURA Mini ITX LGA1151 Motherboard ($125.99 @ SuperBiiz)
Memory: Corsair Vengeance LPX 16GB (2 x 8GB) DDR4-2133 Memory ($74.99 @ Amazon)
Storage: Sandisk Ultra II 240GB 2.5" Solid State Drive ($74.99 @ Adorama)
Storage: Seagate Barracuda 2TB 3.5" 7200RPM Internal Hard Drive ($65.99 @ SuperBiiz)
Case: Phanteks Enthoo Pro M ATX Mid Tower Case ($79.99 @ Amazon)
Power Supply: SeaSonic S12II 430W 80+ Bronze Certified ATX Power Supply ($53.99 @ SuperBiiz)
Optical Drive: LG WH14NS40 Blu-Ray/DVD/CD Writer ($40.98 @ Newegg)
Operating System: Microsoft Windows 10 Home OEM (64-bit) ($89.99 @ NCIX US)
Total: $806.80
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-03-02 02:53 EST-0500
And then you want to add an audio interface which most likely you'll want to get from a separate source, like Musicians friend or whomever you prefer. The motherboard on this system has pretty decent audio, but you'll want midi inputs and separate shielded audio, so you'll want something that's probably divorced from the motherboard like a USB or specialized PCIe unit designed specifically for your needs. You might know all you need to about that, I don't know what your level of expertise is in this area, but I could probably make a couple of recommendations based on exactly what you expect to be able to do with the machine. Or you can research and find the most suitable interface yourself.
Keyboard, mouse and monitor are largely up to personal preference, so unless you totally have no idea on those, I'll also leave that up to your own tastes.
This would be an extremely capable machine, actually probably far beyond what's even necessary at this point, but it would allow you some room to grow in experience and expertise as well, and should be capable of doing what you need for at least the next five years, if not more.