Roon Labs Nucleus+ music server

Sssssshhhhhh—I forget what music was playing, but as the sound faded away, I could hear a loud hissing coming from the 2011 i7 Mac mini I was operating headless with Roon 1.3 to play files over my network. Checking the mini's shared screen on my MacBook Pro revealed that it was completely unresponsive, so I yanked its AC cord, after which it wouldn't boot up.

This was the second time the Mac mini had died. The first time, in 2015, the local Apple Genius Bar had repaired it. This time, the hipster at the Genius Bar turned me away: "We don't offer repair work on vintage computers."

But I'd become addicted to the Roon app. The loss of its host computer was almost an existential crisis.

Vintage Computers
In 1967 I had a summer job working in an electronics lab. Whenever we had a problem that needed to be worked out on a computer, we would present it to a gentleman in a white coat, who would code the problem on punch cards, then disappear into an air-conditioned room to which we "civilians" were barred entry. A few days later, I would receive a printout of the result. That was my first experience of working with a computer.

In 1981, I bought a kit from which to construct a Sinclair/Timex ZX81 computer. Housed in a small plastic case with a plastic-membrane keyboard, the ZX81 was based on a Zilog Z-80 8-bit microprocessor chip and came with 1kB of RAM, which I upgraded to 16k in order to run larger programs that I'd bought or written in the ZX81's BASIC language. That was my second experience of working with a computer.

In 1983, I bought a BBC Micro Model B, which used an MOS Technology 6502 8-bit microprocessor, had enough RAM to be useful, and could be used with 5¼" floppy diskettes. I wrote programs in both BASIC and machine code; by 1985, using a tagged text language I'd written, I was producing on the Beeb most of the editorial content for Hi-Fi News & Record Review magazine. That was my third and formative experience of working with a computer.

But becoming involved at such a deep level in personal computing required way too much time. Over the years since the 1980s, particularly when it came to using a computer as an audio server, I've been working with ready-made solutions—eg, the Antipodes DX Reference, Aurender N10, and NAD Masters Series M50.2—in which all the heavy lifting of optimizing a general-purpose computing system to work as a dedicated server for playing audio files has already been done.

Yes, I've recently been tempted by the introduction of low-cost computer-on-a-board systems such as the Raspberry Pi, the various Arduinos, and Intel's NUCs—but there's that time-sink problem again. The closest I got to rolling my own server was installing Roon on my Mac mini—and you know how that worked out.

Fortuitously, soon after my return from Apple's Genius Bar, Roon Labs' Steve Silberman called to let me know that the company was about to release its first hardware product, the Nucleus+ server. Would I be interested in a review sample?

I would indeed!

Enter the Nucleus+
Roon's COO, Danny Dulai, visited in late February, bringing with him a Nucleus+. Priced at $2498, this uses an Intel i7 processor/NUC board and has 8GB of RAM and a 64GB SSD solid-state drive. The basic Nucleus costs $1398 and uses an i3 processor with 4GB RAM and a 64GB SSD. Both Nucleuses have a single gigabit Ethernet port, two USB 3.0 ports that can be used both to connect external drives and to feed data to a USB DAC, an HDMI port that can be used for both stereo and multichannel audio, and a Thunderbolt 3 port, so far unused. The Nucleus+ can output audio data simultaneously to more than six zones, one of which can be the iPad running the app. The Nucleus can cope with six zones.


The internal drive is not used to store audio files. Instead, as well as hosting the Roon Optimized Core Kit (ROCK) operating system and the Roon server software, it's used to manage Roon's library (footnote 1). From the outset, Roon was intended to produce a rich metadata experience. From the moment you point the Nucleus Core to the location of your audio library, the system begins to create the waveform display for every track; starts scouring the Internet for metadata, artwork, biographies, and reviews; and builds an object database. This means, says Roon, that "instead of storing data in the traditional tabular form, we model your music as a web of interconnected entities and their relationships to one another. . . . They enable us to perform complex queries that would be impractical for a traditionally architected application, and they let us perform background processing on your music library in order to continually improve the user experience."


The basic Nucleus's 64GB SSD can handle the metadata for libraries of up to 12,000 albums or 120,000 tracks; the Nucleus+'s SSD can cope with libraries with more than 12,000 albums/120,000 tracks. I thought I had a reasonably large library; Roon tells me I have 20,565 tracks. The Roon app asks you for a backup location for the library's metadata. After three months of using the Nucleus+, my backup has filled 2.4GB—it's going to be a while before the internal 64GB SSD is full!

Footnote 1: Though the Roon OS is based on Linux, all system functions other than those required to run the Roon server software are disabled. The Nucleus can't, therefore, be used as a general-purpose computer.

John Atkinson's picture
DH wrote:
Roon works with sample rates up to PCM 768 and DSD 512, and isn’t limited as you indicated. The only limitation of rates below these would be a limitation imposed by your DAC.

Accidentally deleted DH's posting, which had been posted twice. Apologies,

I made this point in my review - see the iPad screenshots.

John Atkinson
Editor, Stereophile

tonykaz's picture

I accept.

Thanks for discovering.

Tony in Michigan

bierfeldt's picture

I am running Roon server on a "Vintage" tower. I replaced the hard drive recently and upgraded to Windows 10. Roon is blisteringly fast and the Radio function is better than Apple's Genius.

All of my irritation is due to the Windows PC I am running on as Windows updates cause it to re-boot constantly and I am suddenly having issue with my Airport Extreme. Okay, constantly maybe excessive, every couple days is more like it and I think my network issues are partially my cable companies problem but it is still irritating.

But again, this would solve most of my issues. May pick one up.

Great review.

dalethorn's picture

On my PC (I also have a Macbook Pro) I run Windows XP, which is very stable. If the drive ever crashes, I just go to my tech and get another XP drive and copy my files from my backup drives.

Bogolu Haranath's picture

Apple just released a new 15 inch Mac Book Pro with 4TB SSD built-in storage, 6 core processor and up to 32GB RAM .......... $7,000, if got the dough and willing to spend .............

dalethorn's picture

And all of that "enormous power" filtered through a slow, turgid, sometimes frozen pipe owned by AT&T, Verizon, etc. Oh yes - your IP isn't one of those. But your IP has to use their pipes.

My Mac uploads to and downloads from the Internet - when the Internet is working. Real work gets done on my PC, which is isolated from all networks. It's a heavenly combination.

Bogolu Haranath's picture

5G wireless is coming soon (to a sky near you) :-) ...........

dalethorn's picture

Pay attention: 5g specifies the width of the pipe, not the actual throughput. When cable companies became dominant by the 80s, they established that their pipes to your house were "shared" with nebulous anomolous "persons" in your area. Not as bad as "party line" telephones, but still slow-to-useless at certain times for Internet use.

Now you talk about 5g as though you're offering a solution. You're offering nothing except another shared pipe that brings the same as everything else - poor throughput.

Bogolu Haranath's picture

Ok ......... I Googled it ........... According to the info available on Google, 5G is supposed to increase speeds (as well) ......... You can check it out, on Google, if you are interested ............

dalethorn's picture

How many times do I have to repeat this? 5G is the *potential* or maximum bandwidth. Your provider can dribble the data through that pipe at 200 bytes per second during "peak hours", which they always do.

Pay attention. You will never get 5G speeds consistently on a 5G network, and oftentimes, you'll be begging for 3G speed and still won't get it. Get it?

Bogolu Haranath's picture

"Itsy Bitsy Spider" .......... Carly Simon :-) ...........

woodford's picture

should have taken the mini to tekserve on w. 23rd; they could have fixed it.

John Atkinson's picture
woodford wrote:
should have taken the mini to tekserve on w. 23rd; they could have fixed it.

Tekserve closed a couple of years back. These days I go to Mike's Tech Shop on W. 20th. The cost of repairing the Mac mini was not much lower than the price of a new one.

John Atkinson
Editor, Stereophile

woodford's picture
Thanks- it's been a while since i needed to visit them- sad to hear they closed. in the days before the apple store it was almost the only place one could get a mac repaired.
CG's picture

Have you ever considered trying a test such as this where sample averaging is turned off? Perhaps instead using "Max Hold" or "Peak Hold" over several seconds of sampling time in order to capture random and pseudo-random events?

PeterMusic's picture

That's a long review on a critical product that costs quite a bit to skip the listening notes. Kind of disappointing

rzr's picture

So your mac mini went down 2 times in the last 7 years and you went to the mac store and they said they don't fix older computers. So why didn't you just buy a new mac mini? You rant about how you have all of this computer background, which coming from me with over 40 years of a REAL computer background, you really don't have much computer experience, so i'll call you a hack which dabbles into the computer sector. If you knew anything about computers, you would know that the Nucleus+ is just a computer, and a very expensive 1 at that. What happens when the Nucleus+ won't boot up? What happens when the internal SSD fails? What will you do when an error pops up? You will need to call Roon Labs. Forget about taking it down to your local Apple store or any computer store. If you would have gone out and bought a new Mac Mini with 8GB ram, i7 processor, 1TB Fusion drive with 256G PCI-E flash storage, you would have paid $1200. But if a mac is way over your head to deal with, then go for paying double for another computer and hope nothing goes wrong with it. Before I spend $2500 on a nucleus+, and if I wanted 24/7 computer access, I would buy 2 refurbished Mac Mini's, setup a RAID disk, and if 1 Mac Mini would fail, hook up the other Mac Mini to the RAID disk and off you go.

anonymusicdude's picture

So wait a second. JA uses a MAC Mini and PS Audio DS DAC ? You mean the one that changes every 6 months to a different sound ? lol Sirenus uses a $469 intel NUC ? I thought these guys were Audiophiles ? whats up with that ? wheres the gear boys ? At least have a custom build server like the guy above says except screw Apple BS Linux is far better for a server

vkennedy's picture

There's a huge issue with how Roon Rock running on Linux, and an incompatibility with XMOS based DAC's.

Read this thread:

Scattered accross Roon's forum's are dozens and dozens of reported issues.

mauidj's picture

I am a new Roon user and I am deciding how to set it up in my system. Right now Roon Core is on an iMac feeding the house via WiFi to various different endpoints. But i would like to have a dedicated Core machine directly connected to my main system DAC via ethernet. (or via a bridge???)
I just dont understand why a Nucleus is a better deal than a Mac Mini? A base Mini with storage is half the cost of a Nucleus+ with no storage.
I currently have just over 100,000 tracks on an external HD.
I am a complete digital audio idiot so am I missing something?

shp's picture

Hi mauidj

Why we need these audiophile servers is a bit confusing. And "need" is a strong word.

I use a MacMini wired directly to my main DAC and streaming to my work computer and my phone using Roon.

There are two main challenges with the MacMini:
* System updates often leave the computer stuck. Either the OS couldn't install the upgrade (e.g., Roon or another app was running) or it failed to reboot properly. Roon needing to install server software upgrades can cause similar issues.
* Usually I can resolve the above without needing to access the Mac desktop. But when I can't, it's a whole additional set of steps to revive it.

I can fix it when things go wrong. But my girlfriend can't. To her it's just "not working." Because the Nucleus only does one thing, I would assume it's significantly more reliable.

Additionally, it has been designed to eliminate a lot of electrical noise.

That's not to say that you need a Nucleus, only that it probably does a couple of things better than a MacMini.

ChevChelios's picture

Hi rzr. The Roon Nucleus is merely a NUC - it's right in the name. Why not use a NUC rather than be a condescending A-hole who brags about their computer chops all while proving their sub-par grasp of English.