Nucleus DSP capabilities

I am considering to move my Roon core from Synology NAS to Nucleus. Nucleus specs provide for some limitation in the DSP domain for DSD as opposite to Nucleus +, where there are no such limitations.
It says for Nucleus " DSP capability All DSP functions available in the PCM domain, certain combinations of functions using DSD, upsampling, or multichannel processing may not be possible."
I am upsampling most of the PCM content do DSD using the Roon DSP, using sample rate conversion (DSD 128, Smooth linear phase filter, Sigma Delta modulator some gain, plus Native DSD processing for non PCM content). Will I be able to perform this upsampling with Nucleus? What are exactly the combination of functions not available with Nucleus?

What CPU does your NAS have? In general, heavier DSP like DSD conversation, likes a more powerful CPU.

Don’t overlook, getting a NUC and loading ROCK. Or, a PC and using Windows or Linux.

Sry but that is not the question… The question in what are the DSP limitations on Nucleus vs. Nucleus+ as quoted in the product specs

You are asking for a hard definition where there isn’t one. There are no DSP functions which are NOT available between the models. The line is “…may not be possible.”

Depending on your specific use case, Roon might require a more powerful CPU, which is what the difference is between the two models. The Nucleus uses an i3 mobile CPU and the Nucleus Plus uses an i7 mobile CPU.

Certain combinations of Library size, number of simultaneous endpoints, and amount and type of DSP, can lead to drop outs or skipping if it overtaxes the CPU. The most likely of these is DSD conversions which is why it is singled out, as is multi-channel processing.

I asked what CPU you have currently in your NAS, as a baseline to which you might need. If your NAS is currently running Roon well, with an i3 chip, then you could go with a Nucleus. If your NAS is using something more than an i3 cpu, then go with the Nucleus Plus. Or, just go with a Nucleus Plus if you want to be a bit future-proofed.

Or, as I mention, put together a NUC and run ROCK, or, any PC system which you can just dedicate to the task of running RoonServer. That would give you the option of splitting the difference and using an i5 CPU.

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Thanks for explaining. My Synology runs 4 Core INTEL Pentium N3710 1.6 GHz and has 8 GB of RAM but beyond Roon runs lot of other processes. Despite that and my DSD processing it rarely runs more then 25% of workload according to the system monitor, Roon being by far the most resource consuming process.
I need to move the Core not because of the workload, where it does not really seem to have an issue with but because I need to upgrade this unit to DSM 7, where Roon is no more supported. And I prefer to have then a single purpose dedicated and optimised server for Roon, so certainly not Windows or Mac, hence the questions with regards to Nucleus. NUCs seem to be hard to get nowadays, see my other related post on how to get a certified NUC in Europe as those lines in Amazon are no more available.

Also a Nuclues Plus will for example not able to resample multichannel PCM to DSD256…

I’ve changed my Roon Core some weeks ago from a QNAP (i7, 16GB RAM) to a dedicated fanless Linux server (i9-11900, 32 GB RAM, 2x8 TB SSDs, 1x512 GB SSD), which really support any DSP, which are possible in Roon.
If you know (or want to learn) something about Linux, I would prefer in any case an own builded system and not Rock. With Rock you’re bound (at the moment) to an old hardware, you can’t install any addons, you can’t control the system…

N+'s power is usually needed when you are trying to do DSP on DSD, and not PCM.

There are some cases like certain convolution filters that will require an N+, but how you generate those and how many taps they have is under your control. I could easily build a convolution that would hose even the most capable machines.


I have no problem doing that alone on an N+ (5 channels). It starts to struggle however when I add convolution to that DSD content.


Try eight channels…

Well I will probably give up on Nucleus considering the limitations vs.price. Found a NUC10i5FNH will beef it up to 16GB RAM and will go for this one, hope to give enough power for my basic upsampling. Do not perform any multichannel DSP and do not even think about to do that in future.

I have been running Roon core 24/7 on a NUC10i3FNH for 2 years. Works fine for my library of 7 TB mostly 2 channel classical recordings, 75% in 24 bit FLAC or DSD. I started doing room correction using convolution in Roon lately. It works fine for most files but does get sluggish with FLAC files over 192KHz, DSD512 or higher. So I am thinking to upgrade to a NUC10i7FNH…

I tried a Nucleus in my system and it wouldn’t upsample successfully to PCM Max. I have had two Mac Minis I5 and I7 as Roon cores and they both upsampled to 512 DSD to my two DACs without ever missing a beat. I get - as a trial - the Nucleus on my system as core, works ok for a few days, then on one of the DACs it won’t upsample to PCM Max. Not enough CPU even to do that, very disappointing, so it will go back. Surprisingly though, as I posted in another forum, there was a very pleasant SQ improvement, not massive but enough to wanted me to keep the Nucleus and be excited. ARC was perfect accessing stored files remote too.
I might consider a Nucleus Plus but what I learnt is that you can’t trust that the base Nucleus to run consider basic DSP.

My i3 nuc has no issues and it’s the same spec as board as used in the nucleus it runs rock which is the same base os and can upsample and apply convolution filter for room correction just fine so I would look elsewhere for the issues. Where are your files located, what is you DAC and what is it’s Linux support.

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Thanks for your reply, I note your also replied elsewhere. Files are Tidal, external Saming 2TB SSD out back of Nucleus and internal HDD which I formatted this morning.
Project DAC (my other Denafrips DAC works fine) which is Roon tested so should work well with a Roon Nucleus. I know hifi dealers who have this Project DACs in their second systems and they work great with Roon upsampling and mine has for four years plus.