Should I upgrade from a Mac Mini to a dedicated server or should I upgrade my dac?

Moving the ROON core from my Mac Mini to an SGC ST was the right move for me. Already had a Pi based streamer and a descent DAC.

I can't thank all of you enough for this great advice. 
This is great!
Based on everything you mentioned right now I am leaning towards my initial impulse of starting with a better dac and implementing the other upgrades over time,

I like the idea of integration but only to a point- as appealing as a single box solution may be I'd rather retain the ability to upgrade single components .  That said, I would probably opt for a dac with a bridge/network Roon endpoint- I was thinking of a Bricasti M3 or maybe an M1 SE (really stretching budget here); another audiophile I know well swears by the Manhattan II.  I believe any of these these should be a good step-up from the Moon 280D (though it remains a very competent dac).
The other option of course is a dac without any network card (maybe Aqua La Scala or Holo May) and investing in a separate Roon endpoint- Sonore etc as discussed above.  In other words, spending less on the dac itself and to give more room to an endpoint upgrade. At this stage I'd probably leave the Mac Mini for last in the upgrade process.

In all of this I should mention what I am looking for; first and foremost I would like to eliminate that electronic hash that bothers me, and second I'd focus on a believable soundstage.  Many often refer to soundstage width as an essential element but given the choice I tend to care more about depth,.  And as I have experienced with analog when properly set-up, that sense of space goes hand in hand with "forgetting" about the speakers and all the equipment upstream.  For this I can also forfeit some microdynamics for a better sense of the overall musical event (I sound like an analog person! but don't want to go overboard either as I do care about transparency, detail...and dynamics).

@pgastone that makes sense! Good luck and enjoy the journey!

Thank you!
And if you have any thoughts on the dacs I mentioned or any others that I should consider please let me know.  I am trying to keep myself to a limited budget ($5k-$6k at the very max - preferably $4k or thereabouts) so I will probably look at a preowned dac.
I already mentioned that my priority is a believable soundstage- the other aspect I need to consider is brightness- both the Thiels and Omega Duo horns can become a little hot in the treble if not carefully matched with appropriate electronics upstream.  This is something I will need to look out for.

I have had customers have tons of issues with Mac Minis.  Literally, it created a network issue for a customer so his DAC could not get an IP address.  The mini had to be off whenever he turned on the DAC.  It is not my favorite device. 

Bricasti makes and awesome DAC.  It is very musical and one of the most engaging, enjoyable products I have heard.  I have not heard the Mytek.  The M3 sound bigger but is less refined than the M1 SE.  Bricasti is about dead neutral.  It is warm compared to many units (Chord, Weiss, etc...) but not warm.  

In the $4K range, the Canor DAC 2.10 is a nice unit and has a tube output stage.  It does not have a roon end point incorporated into it.  Highly detailed and a touch warm, it is a nice and easy sounding DAC to listen too.  

The Rockna Wavelight is another good option for a new DAC that will give you a warmer sound profile.  It also lacks a roon endpoint and is a little pricier ($4950 list) but stunningly good.  It is a R2R and delivers what most people think R2Rs should sound like.  

I have never heard a Mytek product outside of an audio show and have not POV on them.  Aqua is supposed to make a great DAC.  It is definitely warmer and would do the job for you considering your speakers.  This definitely should be a brand you should consider. 

I am a dealer for Bricasti, Canor and Rockna and have listened to all of the units extensively.  I am not a Mytek or Aqua dealer.