Software for Room Correction?

What you are looking to do is use the Roon DSP with a convolution filter. Roon has a great post on how to do. I had a person come in and do it for $400 but if you change anything you have to redo. I got the UMIK 1 mic and looked at REW which is free and many have used but I went with Focus Fidelity instead. $250. It was super easy. I can now redo my filters in about an hour or less. 

This only goes to show you how some companies like to tighten the screws into your back when yo think you are buying all of their product.
My brand new NAD came with the MIC. Though it is the same mic that they provided with my old T748 it is probably sufficient to do the job. on the other hand there is the issue with the software. NAD only provided the DIRAClive lite and that might be sufficient BUT... In my case living as an apartment dweller and 70 yr old My hearing is definitely less discerning. The lite version of the software probably covers enough of the frequency band to tune my room, On the other hand for those who don't want crippleware, the extra $100 for the full version of the software, is not too exorbitant a price.
Also I can use the included mic with my phone and the 'Decibel X' software on it. to watch my music at a finer resolution.
I must agree that activating diraclive was a jaw dropping experience for me.

I thought this article was a good read about DSP philosophy from a leading manufacturer: 

http://www.audiodrom.net/en/special-edition-reviews/57-accuphase-dg-58

I have the DSP function of Roon for a couple of years. A year ago I bought a Lyngdorf TDAI 3400 and I am using Roomperfect now. Roomperfect makes it possible to use DSP also while listening to my turntable 😎