Hey @DancingSea
I’ve just re-read your original post… I’m revising my opinion: I think the Zen Streamer is just not the right product for you. You could try upgrading to a linear power supply for the ZS, or adding an EtherRegen before it (is your Zen Stream plugged into a consumer-grade switch?) or a Singxer SU-2 after it, but really the lipstick is getting more expensive than the pig. Try something else (and spend more).
In my experience, I really did have to spend the same amount as my DAC – substantially more, in fact – to get the computer-based chain to sound comparable to a transport (PS Audio PST SACD transport).
To provide some perspective, at retail pricing, my DAC costs X, my transport costs X, and the entirety of my computer-based playback chain (including switches and reclockers and, sigh, cables and everything) costs 2.5-3X.
Back to my terrible metaphor: Running a great server into a crappy streamer is like running an a $3k cartridge and $3k tonearm on a $100 turntable. Does it sound better than the $25 dollar tonearm and $25 cartridge that came with the table?.. sure… but you’re wasting the spend because the performance of the great components get destroyed or filtered out by the crappy one. Keep in mind that the device closest to the DAC has the most impact on the sound of the DAC. I would much rather run a very good streamer, with a basic windows PC running Roon Core, then have a high-end server driving a Zen Stream. Even upgrading the power supply on the Zen Stream would make a bigger difference than roon core hw changes (I’d bet).
I would pick an amount you’re comfortable spending and try something on the used market like an UltraRendu with a linear (i.e. upgraded) power supply to feed your Marantz.
AFTER you have a solid streaming solution, if you want to keep the Roon UI and get better sound quality, you also have to experiment with different protocols, Roon > SqueezeLite and Roon via HQPlayer. This is what I’ve ended up with: a complex grab-bag of playback methods (Roon outputs to HQPlayer for DSD upsampling, I switch over to Squeeze Server / Squeeze Player to play DSD128/256, when I’m not using a dedicated SACD transport) which is, unfortunately, totally worth the results. Squeeze / Squeeze is the ultimate transparency (far more revealing than Roon and Roon endpoint), but Roon upsampled with HQP provides amazing SQ (and perhaps with DSD upsampling slightly slightly euphonic).
So: could you get rid of your Mac Mini and buy, say, an Innuos Zen Mini Mk 3. You would be replacing your current relatively fast computer with a more specialized, and less fast, computer with a relatively cleaned-up USB output. But replacing commodity-cost equipment (your Mac) with another specialized piece of equipment that costs a lot and actually adds very little in terms of functionality, has less storage, etc., and – given that you’re already using a streamer, and that streamer is presumably connected to your home network / router?? – doesn’t do really anything to separate your DAC from the badness of computers and routers.
I could see going to a NUC with ROCK, but I honestly would expect minimal to zero sound quality difference given that you’re using a streamer (and assuming the streamer is connected to your router or a switch, not the NUC of course). You would just be getting better UI performance and less maintenance overhead. Why spend the money that way?
