Is the Roon Nuceus device a good streamer?

You don't "need" a seperate streamer for a Nucleus you can connect it directly to a DAC by USB but you can use a separate streamer if you want. 

I originally set up my system with the Roon core running on my PC and purchased a Bryston BDP-2 (with upgraded audio card) to use as a streamer. I also have a Node2i to compare, and the Bryston sounds a bit better. 

This spring, I built a Roon ROCK core using an Intel NUC in a fanless case so I could put it next to my audio equipment. If you are moderately computer savvy, you can build the equivalent of the Nucleus (same hardware and software) using the NUC in an Akasa Turing fanless case for about half the price of the Nucleus or Nucleus+. I built a fairly high-end config (a bit more powerful than the Nucleus+) for about $1K.  Once built and configured, this offers the same functionality (including auto-updates) as the Nucleus.

For the last couple months, I've been experimenting with connecting my DAC directly to the NUC (Roon ROCK) using USB. The sound quality is virtually identical to the Bryston connected over AES/EBU. 

But there are a lot of variables to consider.

I'm using a ZeroZone linear power supply with my NUC which reduces noise a bit.

I'm using a fairly high-end USB cable (AQ Diamond) and I have not experimented with lower-priced cables. I doubt this has a big impact, particularly with my DAC, but it might have some affect.

My DAC is a Denafrips Terminator which has a very good USB interface. In the case of this DAC, the SPDIF and AES/EBU interfaces are buffered and reclocked by the DAC along with USB, so any clock jitter is determined by the internal clock, not the source clock. So there really isn't any difference in the way the digital data is processed by the DAC. For DACs which derive the sample clock from the SPDIF, Toslink, or AES signal, these interfaces may sound considerably different than USB, depending on the streamer. 

In my experience an Innuos Zenith Mk3 running Roon doesn‘t sound anywhere near as good as running native; the Zenith in Roon beats the Nucleus by a country mile, so: no, the Nucleus is not a top server/streamer

emergingsoul,

There is lots to learn in the new world of digital audio and streaming.  With the Roon Nucleus (or Nucleus Plus), the server is connected to the internet and (in my case) to an external hard drive via the USB connection, the second USB connection for outputting the digital signal to my external DAC.  I also have a subscription to Qobuz for streaming (I had Tidal in the past as well).  So when I access my library with the Roon app, and search for content (like "Beatles"), the Roon server shows my library as the content on my hard drive+the content for the Beatles on my Qobuz subscription.

So, to stream music, in addition to a server, like the Roon server (or a computer) you will need a subscription (like one to Tidal or Qobuz) and output the digital signal to a DAC, which might be built into your amplifier.

I want to stress the fact that I have zero issues with my sonicTransporter i5 when using as a Roon core/server. It has been rock solid and plays all my songs, including several DSP settings for my headphones, without a hitch, My comment about not getting optimal sound when connecting directly to my DAC (Cambridge Audio Azur 851D) in the headphone system is not a shortcoming of sonicTransporter. In all likelihood, it's probably the USB implementation of the DAC or the cable.