After using the Naim app for a few months I have now decided to bite the bullet and take out a one year subscription for Roon. This is after a 1 month trial a few months ago.
I had been impressed by Roon during a trial but not enough to subscribe. I now really appreciate the advantages of Roon. Yes, the Naim app beats it in some respects but overall Roon is worth it.
I have now set the core up on my iMac. It immediately captured all of my iTunes aac files which are repeated on my USB SSD attached FLAC files. I found a setting within settings/library/storage that allowed me to instantly dismiss all of the aac files.
There is a section under main settings/library/storage that allows you to dismiss directories - I entered /Tunes and voila! They were gone!
I have my iMac as core, iPad as controller and NDX2 as endpoint, all connected via WiFi - nice and simple - sounds superb!