Question regarding Nucleus versus Nucleus+

On Roon’s comparison chart on its website, there is wording regarding DSP capability on the Nucleus (as opposed to the Nucleus+) which I would like some clarification on. The website says “all DSP functions available in the PCM domain” - what does that mean?

Also the following wording is ambiguous to me:

“Certain combinations of functions using DSD source or destination formats, upsampling, or multichannel processing may not be possible.“

Its unclear whether references to these functions are conjunctive or disjunctive, i.e. is Roon saying that multichannel processing of DSD/DSF files may not be possible with the regular Nucleus, or alternatively is Roon saying that multichannel processing in general may be a problem for the regular Nucleus?

Any clarification of these two statements (or the differences between the two models for multichannel playback) would be appreciated!


It can do pretty much everything individually but it might not do combinations. By far the biggest consideration is the size of your music collection. After that, how much DSP you may want to use and to how many end points, or how many channels.

It means that the units has enough horsepower to use all the DSP functions for PCM material.

Means that the unit does not have the horsepower to do some DSD DSP transforms

The Nucleus is using an Intel i3 processor; the Nucleus + is using an Intel i7.

As Henry above also mentions. Size of library is also a big contributor to the cpu you want to use to run your library.

Thanks, so if most of my collection is multichannel (at least 1TB of multichannel FLAC) but hardly any of it is DSD/DSF, would I be OK with the regular Nucleus?

Are you planning on using any DSP? What are you playing the music to and how are you connecting the Nucleus to the DAC?

I don’t really know what DSP is. I will be using the Nucleus to decode mostly Hi-Res multichannel FLAC files and stream via HDMI to an Oppo 205, using the Oppo’s multichannel DAC (analog outs).

I am looking for clarity on whether the above quoted statement can be read as “multichannel processing may not be possible” with the Nucleus (whereas no such limitation is listed with the Nucleus+)

DSP would be Sample Rate Conversion, Procedural or Parametric EQ, Convolutions, Crossfeed, some Speaker Setup and Headroom Management.

I read it as saying that the Nucleus may not handle “multichannel processing” as in applying above DSP to a multi-channel stream. Playback is not processing.

However, since you are basing your purchase on this, you should wait and get a response from official support, I’m just a helpful user.

On a side note, the way you are going to setup seems fine. PC > HDMI > Oppo> Analog>AMP. However, due to limitations in the OPPO, you will not be able to stream DSD or multi-channel into the Oppo via Ethernet.

Thank you, very helpful and understood on the Ethernet limitation (no multichannel) through the Oppo.

I am hoping for official word on my inquiry from Roon too; I tried emailing Roon and my dealer has an inquiry into them as well so I’m sure it’s just a matter of time before they get back to one of us.

Thanks again!

I’m sure Nucleus+ does, and it works on normal Nucleus too (I have a loaner from my dealer) but sometimes it hangs up and I’d like to know if that’s a limitation of the Nucleus that having a Nucleus + would fix.

Well, that is a different question, there may be other things going on causing it than just a Nucleus/Nucleus+ difference.

Can you describe how you have the media attached? Is it on a local attached USB drive or on a NAS?

You mention it is a loaner, it is possible it might have not finished analyzing your files. You can tell by going into Settings / Library and see if it shows an analysis count (also there could be a spinning circle i the top right corner of Roon).

The multichannel is currently on its own hard drive (HDD) attached via usb to my synology NAS (DS 718) which is all SSD; if you think having the multichannel available through SSD is likely the issue I was planning on pulling it all over anyway, I just don’t want the issue to be the Nucleus (but I also don’t want to spend an extra $1k or more on a Nucleus+ if I don’t have to).

Thanks again!

Well, I always keep the audio files local to Roon Core, rather than over the network.

Did you verify that the audio analysis had finished? When you said hang, I assumed you meant playback dropped. Or did you mean, the whole machine froze and you had to reboot?

Yeah my library had been scanned already. Both have happened (I’ve needed to reboot once but more because no sound over hdmi) but mostly playback not working on multichannel files only.

Just posting again to keep this thread alive in the hope someone from Roon will post in here.

Jim, have you read the whole thread?

He has a nucleus on loan for testing and it is having issues with multichannel files and was asking if the + would be better. And is waiting for @support to respond

Have you noted your processing speed in periods where the problems occur? You can find that by clicking on the ‘shiny star’ signal path icon next to the song title being played. It’s near the top of the signal path.
Typically, when the processing speed starts to bog down and cause dropouts (like DSP upsampling with DSD), you’ll see the speed drop below 2x. What is happening to you could be separate from the Nucleus processing abilities, but this would be a good data point to note.

Thanks I’ll take note

Keeping alive until Roon hopefully responds

Hello @James_Monagle,

Thanks for your patience, I wanted to confirm things with the tech team before responding.

The regular Nucleus will happily handle bit-perfect PCM multi-channel playback.

Enabling Roon’s DSP features while playing multi-channel content may result in situations where the Nucleus’ CPU cannot keep up. This depends on the complexity of the DSP setup as well as the number of channels + sample rate of the media.

Simple DSP operations like parametric EQ should still work on Nucleus with headroom to spare. Where you will most likely run into issues is using Roon’s convolution engine or sample rate conversion.


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