Musical Fidelity MX Stream Streaming Transport Reviewed

Musical Fidelity’s MX Stream is the latest product to join the long-standing MX range of half-size hi-fi. The range currently includes a phono stage, headphone amp, DAC and now a streaming transport and is, to my mind a premium competitor to the Box Design range of sister company Pro-Ject Audio Systems. One could argue that Audio Tuning, parent of both companies, have rather shot themselves in the foot here with two ranges so similar, yet there’s an undeniable distinction that still sets the Musical Fidelity products apart.

Pro-Ject entered the streaming market some years ago through a partnership with Volumio, creators of the open-source streaming software of the same name that is widely used in the DIY market on small, single-board computers like the Raspberry Pi. What started out as, and still to a degree is an open-source project now has closed components, a subscription model and an OEM division, as well as a range of Volumio’s own hardware streamers both in transport and all-in-one form. There’s an ever-growing list of OEM streamers on the platform too including the Ifi ZEN Stream, several models from Project’s Box Design range and of course the Musical Fidelity MX Stream.

Half-size hi-fi is a concept I like a lot, though the smaller size doesn’t necessarily mean a compromise on features. The MX Stream packs a quad core ARM-based architecture with multiple regulated power supplies, high-grade clocks for the CPU, Wifi, power supply and USB circuits, and a bit-perfect streaming platform claiming ‘near-zero jigger’ into a component measuring just 220 mm wide, 215 mm deep and 56 mm high. The front of its solid aluminium chassis is a cut-down replica of larger Musical Fidelity components, and is of a minimalist look with only two switches, a few status LEDs and a USB port. I wouldn’t mind a few transport controls and a programable IR sensor here, for quick track changes, play / pause and remote control without accessing the web interface.

Around back are a further pair of USB ports, one intended to connect to a DAC supporting USB Audio class 2.0, and the other for a USB storage drive or CD drive. There’s an ethernet jack for hardwired connections, an SMA screw-type connector for the included wifi / Bluetooth antenna and a HDMI display connector.

The final socket is a USB B connector. To this you can connect your computer, streaming audio to your DAC via the MX Stream’s USB detox process which cleans up noise on the USB line for the best possible data signal. In practical terms this means less error correction and in theory better sound, though whether the difference could be measured objectively or heard subjectively is debatable. But it’s nice to have the option to hook up a computer without disconnecting the streamer. The right-most front switches toggles between the connected computer and the MX Stream’s internal streaming output.

Lastly on the back is a ‘boot’ button, which puts the MX Stream into a mode whereby it can be flashed with an operating system of your choice in the same way you’d flash an SD card to boot a Raspberry Pi. It is therefore possible to run any platform on the MX Stream hardware – MoodeAudio or PiCorePlayer for example, if Volumio isn’t to your taste. Keep in mind though that the original software image isn’t available for download on the Musical Fidelity website at the time of writing, and it’s not clear whether they’ll provide this on request so if you choose to experiment, you do so at your own risk. It does at least mean that the MX Stream will remain useful into the future if support for the Musical Fidelity OEM Volumio platform is dropped.

Lastly there’s a 2.5 mm DC power connector for the included power supply. The MX Stream is powered by an 18V 1A wall wart as standard. It’s one of those horrible lightweight things that Pro-Ject supply with a lot of the Box Design kit which to these highly sensitive ears emits an irritating whistling sound in use and injects spurious radio frequency interface onto the mains supply that messes with nearby wifi devices and radio tuners. I’ve nothing against a switch-mode power supply if it’s a good one, but this one isn’t. At this price a decent power brick should be included. A medical-grade switch-mode power brick costs around £30 and I’d advise you factor one into the cost of an MX Stream purchase.

Build quality is great across the board. I’m not a fan of the front switches which are momentary toggle switches that are pressed down to activate them. They’re tiny, fiddly and not at all nice to use. Pushbuttons would have been a far better choice here. Switches aside though the MX Stream is well put together and looks neat in a system, where other streamers look more like games consoles or networking hardware than hi-fi components.

Setup is a doddle too. When powering on for the first time the MX Stream enters hotspot mode, unless it detects a wired connection. You use any wifi-enabled computer, tablet or phone to connect to the hotspot, and the web interface should appear. If it doesn’t type musical-fidelity.local into your browser. Then in the settings you can configure your wireless network, and in a minute or so the streamer is online.

Beginning in the settings, there are a few things I always do to any Volumio installation. Enable the ‘full settings mode’ to get the best experience. This gives you access to the following additional settings and their default functions: Audio resampling (off), Volume normalisation (off), Audio buffer size (2MB), Buffer before play (10%), Persistent queue (on) and Playback mode (Continuous) or Single. Most of these settings are optimal can be left alone. If you have a fast internet connection, increasing the buffer size and buffer before play variables may help to reduce stuttering or dropouts that can sometimes occur with busy streaming servers, though with a compromise in load time and always being slightly behind the live broadcast.

I recommend setting the ‘mixer’ setting in the playback settings to ‘none’ unless you want the MX Stream to control the volume. You’ll also want to select your DAC and run a check for software updates, all of which can be found in the various settings pages. It’s all self explanatory, and there is plenty of documentation to help you along the way.

Volumio also has an area for developers that gives you access to a few more options, and this is true for the OEM versions too. You access it by navigating to streamername.local/dev (in this case musical-fidelity.local/dev). Here you can enable test mode to receive beta software updates, which can give you early access to the latest features. Keep in mind that the software will not be fully supported, may contain bugs, and may even be entirely unstable. But if you’re an advanced user and you know how to troubleshoot when things go wrong, this can be to your advantage. At the time of writing, the latest test software introduced Tidal Connect as a feature which is something I know many will be glad to see.

You can also enable SSH from the dev panel, to get command-line access to the streamer’s linux-based operating system. Unfortunately Musical Fidelity don’t publish the login credentials and they’re not the standard Volumio details, so I wasn’t able to access the MX Stream via SSH. This would be useful for advanced users as these streaming devices have a lot of wasted computing power that could be put to good use – running servers, smart home automation, even control over a hi-fi system with a USB IR blaster or USB serial adapter just to name a few examples. You could also gain access to configuration that is not available in the web interface, such as CD ripping configuration. Hopefully Musical Fidelity will release the SSH login details, or ship the streamers with a user account especially for DIY tinkerers.

Back in the dev panel and there is one other interesting feature – full statistics. I’ve not seen this before in a Volumio installation. The stats give you the streamer’s internal temperature (presumably from sensors on the SOC itself), network connection information, and even the current power usage and input voltage. It showed that the voltage drop on the included power supply was relatively significant under load. It’s a neat feature that should really be included somewhere in the main interface.

The main interface and it’s pretty much standard Volumio with three notable exceptions in the form of toggles for AirPlay, Bluetooth and the USB bridge. These are all off by default, and in the current software version at the time of writing are not persistent – meaning they are disabled each time the unit is rebooted. This is frustrating as to connect via AirPlay or Bluetooth requires the additional step of accessing the web interface to toggle the function. The USB Bridge function can be switched with the button on the front of the unit, but there’s no way to re-assign this button to control AirPlay or Bluetooth if the USB bridge function isn’t used.

AirPlay does work perfectly on the MX Stream, unlike on the Ifi ZEN Stream (review coming soon) which is also running Volumio. It connected faultlessly to several devices and worked without a single dropout, with great sound quality across the board.

Everything else is where you’d expect. There’s an internet radio directory, though notably missing all BBC stations besides the BBC World Service. You can at least add your own stream URLs, and set a list of favourites and presets for later recall. The music library can stream from connected network drives, DLNA / UPNP devices and USB mass storage devices such as hard drives, USB sticks or an SD card in a USB card reader.

You can connect to network shares regardless of whether they are DLNA servers or not. You can also connect up as many mass-storage devices as you like theoretically providing you use a powered USB hub. All of which will be scanned for content and catalogued in the Volumio database. The database is stored on the MX Stream itself which has 16GB of internal memory. There are no setting to change the storage location of the database, and there’s no telling how big a library you’d need for the database to reach the limitations of the free space on the streamer, but it’s highly likely you’ll never find the limit. You can browse the database with a number of filters (artist, album, genre etc) and there’s a search function which works efficiently.

CD ripping is a welcome feature too. Connect up a CD rom drive and the MX Stream supports bit-perfect CD playback, and can rip and encode your CDs to lossless FLAC files. It supports metadata lookup and tagging and works well. There are no configurable options though – you can’t set the file format or quality, adjust the tags, set the drive speed or automatic eject, or even have the MX Stream automatically rip or play a CD on insertion. Most streamers can’t rip a CD at all so this is a step in the right direction, though it could use a bit upgrade in functionality to be a true substitute for even the most basic ripping software.

You don’t get access to the Volumio plugin repository, and as you can’t access the console via SSH there is no way to install plugins on the unit. There are some better internet radio implementations, some equalisation and room correction plugins and even a more comprehensive CD ripping plugin that would be useful enhancements if they were available. As it is the MX Stream’s feature list is comprehensive by audiophile streamer standards, but a few tweaks in the software would make it richer in features than all of them.

Sound wise there isn’t much to report. The MX Stream is a network bridge, serving up content to your DAC of choice. If it imparted any character of its own, it would be broken. But it doesn’t – it outputs bit-perfect digital audio at any supported resolution, exactly as it is supposed to. I don’t have an audio analyser to measure the MX Stream, but I highly doubt its output would be objectively distinguishable from the highest resolution source files, and the same is certainly true subjectively.

The MX Stream is a compact network streamer running refined software and with enough features to suit most needs. Yes, there are network bridges that do the same thing for less money – exlucidn gate DIY route, which is always cheaper. To an extent you are paying for fit, finish and a brand, but that’s true of most products in audio these days. It could use a few software tweaks and feature additions, and I’d like to see some additions to the hardware too. Those front switches need to be replaced with real buttons, I’d like to see some more physical controls on the front panel, and the included power supply simply isn’t good enough at this level. Nevertheless I can’t fault it as a network bridge, as it delivers bit-perfect audio to your DAC of choice and does so without character, noise or fuss. For that it earns my recommendation.