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Roon Nucleus Test: A multi-function, multi-protocol and multi-zone audiophile hub!

Door Alban Amouroux |

Roon Nucleus Test: Roon has received a great deal of attention as it has been successfully implemented in many HiFi products, from the most accessible to the most prestigious. Over time, Roon has become an essential tool for playing high-resolution dematerialised music, but not only that... Roon can also bring together music services and a personal file library that goes much further in terms of both ergonomics and functionality. The Roon Nucleus is a global controller that manages the use of Roon.

To understand the full power of Roon, it is first necessary to understand how it works. First of all, its purpose is to play high-resolution audio to one or more compatible digital audio players: streamers, connected amp, wireless speakers etc. Roon supports three different sources: integrated music services such as Qobuz, your audio file collection and internet radio.

The Roon Nucleus is not a server. That’s not its primary function anyway. It is, above all, the conductor of your hi-res audio system. All Roon related actions such as control, playback, file management and audio processing will be done through it. As an accessory, there is a free slot inside to install a hard disk and add the server function. Its various USB and HDMI ports also allow it to be used as a Roon audio player.


Roon Nucleus

● Price : €1,649 / Nucleus+ €2,799
● Includes 1-year Roon licence
● Roon Core with optional audio server & Roon Output functions
● Nucleus : Nucleus: Hi-res audio, integrated Qobuz, online radio, management of up to 100,000 local music files, up to 6 zones, limited DSP processing
● Nucleus+ : Nucleus+: Hi-res audio, integrated Qobuz, online radio, unlimited music files, number of zones and DSP processing
● Connectivity : 1Gb Ethernet, 2x USB-A 3.0, USB DAC and storage media compatible, 2x HDMI multi-channel compatible, 1x 2.5” internal SSD slot
● Dimensions (W x D x H): 10.5” x 10.5” x 2.5”
● Weight : 7lbs  

The Main Role of a Roon Core

There are already many audio playback protocols via the network, whether they are universal (AirPlay 2, Chromecast, DLNA) or proprietary (Sonos, HEOS, MusicCast, BluOS). Roon has developed its own: RAAT which stands for Roon Advanced Audio Transport. As a comparison, let's take the example of the AirPlay 2 protocol. It works as follows: on an iPhone, you select a track from the Qobuz app and send it to play on an AirPlay 2 compatible audio device. The link is direct.

With Roon, you must use a Roon app (PC, smartphone, tablet). This app communicates exclusively with a physical device, the Roon Core. Once you have selected the music, all that remains is to send it from the Roon Core to a Roon compatible* player (or Roon Output). We say “compatible”, because the server supports several playback protocols: RAAT, but also AirPlay 2, Chromecast and Sonos. In any case, to use Roon, you need a Roon Core that acts as the system’s brain, which the Roon apps communicate with.

What's Inside the Roon Nucleus?

The Nucleus is nothing other than a PC dedicated to music. Its components and its design, which were developed in collaboration with Intel, are aimed at the ideal processing of music streams, without fans or any moving mechanical parts. Passive cooling is generated through the aluminium chassis with large blades. This reinforces its robust look. It has no buttons, except for the power button, and no lights. The Nucleus is compact, modern and silent: there is no need to hide it away.

The rear connectors include a Gb Ethernet socket, two 3.0 USB ports and two HDMI sockets. The network link must be wired to avoid relying on a congested or poorly performing Wi-Fi network. The USB ports allow external hard drives to be connected for file storage, in addition to the internal 2.5" SSD slot. They are also used to connect one or two USB DACs for direct audio output. The HDMI has the same purpose while allowing multi-channel playback via a home cinema amp for example.

There are two versions of the Nucleus: the Nucleus and the Nucleus+. They differ in their embedded processing power. The former has certain limitations like the number of files in the library, the number of playback zones and sound processing. The Nucleus+ has no such limitations. However, the classic version should be sufficient in the vast majority of cases with a maximum of 100,000 files and 6 playback zones.

What Functions Does the Roon Nucleus have?

As a Roon Core, the Nucleus first of all makes the link with the app. It stores all the information related to your Qobuz subscription and your music library and presents it in accordance with different criteria. This allows it to mix all content for a unified and transparent search. For example, the Qobuz playlists and your library playlists are gathered in one place. Both systems are laid out the same in order to offer consistent and pleasant navigation.

All audio streams pass through the Roon Core. When you select a track on Qobuz, this passes through the Core and is then sent to the selected player. If you listen to six different tracks in six zones, then all six streams pass through the Core. This large amount of data it needs to process accounts for the limitations of the classic Nucleus, which is less powerful than the Nucleus+.

However, running everything through the Core offers a unique advantage: whatever the quality and format of the source and whatever the playback capabilities of the selected device, the music will always play. The Nucleus adapts the audio stream to the capabilities of the playback device in real time. For example, if a wireless speaker only accepts 44.1kHz/16-bit, then the 192/24 hi-res audio stream will be converted to 44.1/16 on the fly. The same applies to file formats. The Nucleus will be able to send DSD to any player that does not support this format because it performs the prior transformation into another accepted format.

By using this feature to control all audio streams, the Nucleus can enhance them by applying digital processing. For example, you can manually change the sampling rates. When adapting room speakers, the Roon Core can apply parametric equalisation, a channel mixer for headphone listening or convolution filters for the more experienced. All these settings are specific to each listener and stored in the Nucleus.

The Nucleus in Server Mode

By default, the Nucleus doesn’t have a hard drive. It doesn’t store music, it catalogues (via the network) your library stored in a shared folder, on a NAS server for example. You can however add a 2.5” SSD to the Nucleus by removing the bottom panel held in place by four screws. SATA connectivity is already present.

You can also add one or more external USB drives. All the files contained on these different storage media will then make up the library managed by the Nucleus. You can add as many music folders as you want by mixing internal storage and shared folders on the network.

If your CD collection is not yet digitised, a USB CD-ROM player can be connected to the Nucleus. The Nucleus then becomes a copy station. CDs are automatically scanned in FLAC format to the internal drive or a USB drive. Once the CD-ROM player is connected, the Roon Core interface adds a “CD Ripper” section which allows the current disc to be ejected if necessary.

The Nucleus in Player Mode

As soon as the Nucleus is configured, it automatically recognises compatible players on the network in the various RAAT, Chromecast, AirPlay and Sonos protocols. Each control device, whether it’s a tablet, smartphone or a PC also becomes an independent playback point.

Roon recommends using one or more independent players for better load balancing: each one has its own function! However, you can use the Nucleus as a player thanks to its USB and HDMI sockets. For example, you can connect one or more USB DACs to create multiple audio zones. The HDMI sockets can be connected to home cinema or to Hi-Fi amps. Note, this is a classic HDMI and not a HDMI ARC. We connected two USB DACs and a home cinema amp at the same time to create three zones without any difficulty. The audio quality will obviously depend on the connected equipment. The Nucleus simply provides them with audio streams in the best possible definition.

The Pros :
Ready-to-use Roon Core
Compact and silent
Multi-room and multi-protocol support
Universal hi-res compatibility
Digital audio processing
Scalable to server, CD copier, player

The Cons :
High-end price
Lacks Qobuz playlist management


The Roon system achieves a kind of perfection in ease of navigation, integration of hi-res solutions as well as multi-room and multi-protocol streaming. Roon evolves regularly to perfect the interface and functionalities. Qobuz is fully integrated into Roon with access to all the usual sections. Roon displays all the editorial content by Qobuz linked to albums, artists and different contributors with multiple interdisciplinary links. Only one function is currently missing: the possibility to create, modify and add tracks to Qobuz playlists from the Roon interface. The Nucleus is the essential and immediately ready-to-use tool to form the heart of your Roon system. It can also act as a server, CD copier and player via a USB DAC or HDMI. Finally, Roon can be connected to a home automation system via extensions reserved exclusively for the Nucleus. It is a high-end and universal audiophile tool that has no equivalent on the market.

Click here to find out more about the Roon Nucleus.