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

@verdantaudio 

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. 

Was this with a Bricasti DAC? And was it with Roon?

@verdantaudio that’s strange. I’ve been using Mac Mini in my system since 2008. First one died after 11 years of pretty much non stop service. The 2018 version is still going strong and is being used only as Roon core.
Granted, the Mini isn’t an awesome streamer by any stretch of imagination but it’s totally fine as a Roon core.
 

I never ran into network problems with it. Other issues like Mac OS upgrade induced Roon bugs yes, could be annoying.

What you’re describing sounds like some sort of a firewall and or compatibility problem with ISP, DACs etc

That’s bizarre….

I’m using Mac Mini as a roon core (I think it’s the 2018 version with 128gb SSD). No issues. 
I would keep the roon core away from the system and use it purely as Roon Core. Then run Ethernet into the streaming DAC from either the router or an access point. In both cases use EtherREGEN or a network filter between router/access point and the streaming DAC. 
Now to your question…upgrading the DAC in your setup, IMO, will reward you with a more noticeable improvement than upgrading the Roon Core. There are good options for a streaming DAC that are certified Roon endpoints,  either within or outside of Moon product line. 

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