Review: Mass Fidelity Relay (DAC Bluetooth)


Mis à jour le 26 February 2019.

Le DAC Bluetooth Mass Fidelity Relay a des prétentions audiophiles
The DAC Bluetooth Mass Fidelity Relay claims audiophile quality

Is listening to hi-fi quality music using Bluetooth possible? That’s what we wanted to find out when we tested the intriguing DAC Bluetooth Mass Fidelity Relay. A new arrival to Son-vidé, this little box is worthy of audiophile performances, thanks in particular to the use of a Texas Instruments Burr Brown PCM1502 converter.

On paper, an ideal device for listening to Spotify, Deezer or your collection of MP3 files from Google Play Music, smartphones or hand-held tablets.

Before we start our review of the Mass Fidelity Relay, let’s remind ourselves how Bluetooth wireless connection operates and what the apt-X transmission consists of. Bluetooth is a wireless communication protocol with a low bandwidth, whose range is approximately 10 metres in open space. Its genuine bandwidth is roughly 350 kbits /sec, i.e. a quarter of the bandwidth required to stream a CD quality stereo audio stream. Any audio stream transmitted in accordance with the Bluetooth protocol is compressed and consequently damaged.

Le DAC Bluetooth Mass Fidelity Relay est élégamment  fini
The DAC Bluetooth Mass Fidelity Relay is elegantly finished. Note that the logo is white, not black.

Several codecs (compression/decompression algorithms) are generally supported by the peripheral source (computer, smartphone, tablet, etc.). The most common is called SBC and it is responsible for the bad hi-fi reputation of Bluetooth audio streaming. The implementation of this codec in peripheral sources is unequal, with a variable compression rate determined by each manufacturer.

Another well known codec, the MP3, allows transmission of MP3 files without any recompression. Apple implements the AAC codec in iPhone, iPod and iPad from the iOS version 5, which allows a recompression-free streaming of M4A (AAC) files. The apt-X codec also uses AAC compression, which can be applied to CD quality WAV or FLAC files. Music is quickly encoded with an excellent level of quality, even though the signal is damaged.

Is this lossy compression an obstacle?

To be honest, no. Those of you who have listened to FM radio for hours on end know that you can still enjoy listening to a compressed audio signal. As regards hi-fi listening, the quality of the audio stream is less important than the way in which this audio stream is decoded and converted to analog signals. The DAC Bluetooth Mass Fidelity Relay pulls out all the stops.

Packaging contents

The packaging contents of the DAC Bluetooth Mass Fidelity Relay make a good impression with their intelligent individual compartments. The device is held in place with shrink-wrap plastic film, while the individual accessories (power supply, antenna, cables) are held in place in a covered compartment. The DAC Bluetooth Mass Fidelity Relay is contained in a quality brushed aluminium case.

Le packaging respire le sérieux, avec un logement fermé pour les accessoires.
The packaging is serious with a closed compartment for accessories.

Test configuration

We listened to the Mass Fidelity Relay Bluetooth DAC with a Rega Brio R amplifier, a Denon Ceol N8 amplifier and JBL Studio 530 speakers. We initially used the cables supplied with the DAC, then Viard Audio Premium HD RCA modulation cables. For speaker cables, we used Viard Audio Silver HD12 (excellent quality) then Audioquest Rocket 88. As for the Bluetooth source, we used an iPod touch, a Galaxy Note smartphone and a Nexus 7 tablet (2012).

La connectique est simplissime, avec une sortie RCA stéréo. Notez le bouton de mise sous tension.
Connectors are extremely simple with an RCA stereo output. Note the power button.
L'antenne se visse simplement et offre une meilleure réception.
The aerial simply screws in and offers better reception quality.

Installation and configuration

You simply have to screw in the little aerial supplied, connect the RCA cables and power supply. Activation is carried out via a button. The diode on the front panel turns from red to bright blue. With your smartphone, you can look for available Bluetooth devices (less than 10 m from the DAC) and combine them with the Mass Fidelity Relay. Any music played from now on is via the DAC Bluetooth.

Le DAC Bluetooth Mass Fidelity Relay connecté aux cables RCA Viard Audio Premium HD
The DAC Bluetooth Mass Fidelity Relay is connected using Viard Audio Premium RCA cables

Some tracks we listened to

L'album de Janelle Monae écouté depuis Google Play Music nous a emballé
L’album de Janelle Monae écouté depuis Google Play Music nous a emballé

Bowier at the BeebAt the heart of the DAC Bluetooth Mass Fidelity Relay is the Texas Instruments Burr Brown PCM5102 digital-analog converter, a chip capable of working over 24 bits and 192 kHz, used more and more (see new range of DAC and DAC Teac amplifiers) in converters compatible with 16-bit coded audio stream and 44.1 kHz, like this Mass Fidelity Relay.

Our test involved listening to a selection of MP3 files stored on-line in a Google Play Music account, encoded at 320 kbps from FLAC files. On Givin Em What They Love by Janelle Monae, the Mass Fidelity Relay soon eased our concerns ? listening is airy and dynamics don’t seem to be compacted. The treble seems slightly overpowering, which consequently enhances the medium and bass is very much present, providing volume. Listening to a few David Bowie tracks confirms this and we’re surprised to discover as lively a sound stage for an MP3 file.


It’s difficult to dispute this DAC Bluetooth’s hi-fi performances. Listening is clear, detailed and free of any compression. Treble is crystal-clear and bass is convincing. You don’t need to use hig-endRCA cables (silver plated) with the Mass Fidelity Relay, as the manufacturer has optimised the device for a clear and bright listening experience with the cables supplied (OFC copper). The Mass Fidelity Relay is without doubt, the ideal device for wireless music transmission without relying on a WiFi or Ethernet local network.

Share your opinion!

This site uses Akismet to reduce spam. Learn how your comment data is processed.