There may be "additional" steps required to set up your Roon on mac, you maybe need to go and research the settings. I have never used Roon until like five days ago but upon installing Roon app on my Mac, then going through additional settings which are required by Roon to configure "any" audio sources that are connected or can be connected via your Mac.
Long story short, there is no trick, no hack for making your MA mini-i to work via Roon app on Mac and using your iPhone via Roon Remote app as your remote. It just not as straightforward to set up as it should be. This really isn't something to blame Matrix Audio but rather of UI design by Roon app, which doesn’t make the whole process more simple.
I would suggest, to go and check all the possible settings for any connections found in your Roon app that is running on Mac. You most probably missed something or have something set up the wrong way.
Note: when you are configuring your MA mini-i to work via Roon app, remember which USB connection on your Mac you were using, as for some reason if you don't always plug it in that same USB port it will not be recognised (or it may not be) be recognised by Roon unless you go through the set up process again for other USB port. I would blame Roon app for this, the audio source once configured in Roon should be re-recognised independently of the USB port which is being used.
In any case, I can confirm that MA mini-i works without any issues when you use a Roon app on your Mac as an intermediary. What we don't have yet is MA mini-i pro to work with your iPhone without the MacBook as an intermediary. For that that certification process needs to be completed.
There are two Roon apps in the App store, one is called Roon Remote app, the other is Roon essentials remote app …which is confusing and has an important distinction. For the case discussed here you need to use Roon Remote app which will then connect to Roon app on your Mac.
If and when MA mini-i pro will be certified by Roon, we will be able to use Roon essentials remote app, which works without the need to connect to Roon app on your Mac. This was implied in app descriptions when I checked.
I am really new to all of this audiophile stuff but consider to be an advanced user when it comes to computers and I must say Roon set up process is not user-friendly for use case which we are discussing here. I had no issues but I would be surprised if an average user wouldn't find it confusing and missing a step or two, needed to make this work from the get go.
That being said, if Tidal connect can/will be implemented via future firmware update, this would offer a far superior user experience in terms of simplicity, not to mention saving on money. You would just use your Tidal app which you already have and that’s that …no other set up, apps or services needed at all.
As a first-time Roon user, I find little to convince me why would I pay for it? When playing the same playlist over MA mini-i pro via USB connection, I find the listening experience via Tidal superior (master subscription option). Roon seems to offer a bunch of additonal settings which may benefit those who need some custom set up to get the most out their specific audio system set up and/or those who own a precious library of master audio files. I on the other hand primarily use my MA mini-i pro paired with Topping A90 for listening via headphones via streaming subscription service when working on my computer. Tidal sounds better out of the box to me, while I need to play with settings on Roon to try and match what Tidal gives without any config (other then checking if Use Exclusive Mode and Passthrough MQA is enabled). I have been switching between the two (Tidal and Roon) for a few days yet find Tidal experience more consistent across the board and better sounding for my use case.
Your experience may be different but this is my take as newbie to all of this, I really have no biases to neither Roon nor Tidal and if it were up to me, I would use Spotify as I find their algorithm for discovering new music superior to all others …yet unfortunately for me, Tidal really has convinced me when it comes to sound quality, which is why I am using both Spotify as Tidal for the time being.
Tidal Connect, for me please, if possible