Media Server Reviews

Back in May 2014, I reviewed NAD's Masters Series M50 Digital Music Player ($2499) and M52 Digital Music Vault ($1999 with 2TB storage). At the 2017 Consumer Electronics Show, NAD announced the M50.2, which is almost identical to the original M50 but now incorporates two 2TB hard disks, arranged as a 2TB RAID array, to ensure data integrity, and adds TosLink and coaxial digital inputs, Bluetooth with aptX for streaming music from a smartphone or tablet, and two single-ended analog inputs—all for $3999, or $499 less than the combined cost of the two earlier products. Like the M50, the M50.2 offers WiFi and Ethernet connectivity, and has a CD drive, accessible via a slot on the front panel under the color TFT touchscreen, that can be used to play CDs, or rip them as FLAC, WAV, or high-bit-rate MP3 files.

The M50.2 will play files with bit depths of 16 or 24, and with sample rates up to 192kHz. DSD playback is promised by the end of this year. There are no analog outputs, but the digital outputs include HDMI, AES/EBU, and optical and coaxial S/PDIF. Playback and control of the files stored on the M50.2's hard drive can be either via the touchscreen, which displays the album cover and metadata, or via the BluOS app running on a tablet or PC. (Android and iOS devices are supported, and the app is available for Windows and OS X.) The M50.2 will integrate with third-party control systems—Control4, Crestron, RTI—to allow it to be integrated with smart homes. It can also be a Roon endpoint, as all BluOS devices are Roon Ready.

NAD called the M50 a "software-defined product," and the same is true of the M50.2, which is also based on an ARM processor. According to an e-mail from Greg Stidsen, NAD's director of technology and product planning:

"Conceptually, the M50.2 is meant to replace a computer and NAS for what's been known as 'computer audio.' While computer audio can be made to play high-rez music well enough, it does not give the same attention to sonic detail as a dedicated device that integrates these functions and focuses solely on music storage and playback. And if you're not a computer geek it can be very difficult and frustrating to setup and maintain a competent computer based system.

"From a hardware point of view, BluOS is tightly integrated with the hardware platform, meaning we use our own custom drivers to control all aspects of the signal chain. We do not include a DAC in the belief that most customers at this level have a strong favorite amongst the many fine DACs available. More and more amplifiers are also including high-performance DACs (certainly true at NAD) so we felt an internal DAC would only add cost and make people pay for something they may not use."

Stidsen offered these thoughts on the M50.2's construction: "Internally we have paid special attention to circuit layout, which is so critical with high-speed digital circuits. Multi-layer printed circuit boards with large ground planes keep the signal very clean . . . [with] high-quality clocks and quiet and stable power supplies."

Setup
I connected the M50.2 to AC power and my network router and switched it on with the rear-panel switch. An icon for the NAD, labeled "m502.0a13," appeared on my laptop's screen, but the button to the left of the M50.2's front panel flashed alternately red and green to let me know that the firmware was being upgraded. Once it had finished downloading the new version, the M50.2 rebooted itself and I could load music into its internal storage. This was as simple as dragging'n'dropping the files from my iTunes and hi-rez libraries into the "m502.0a13"'s "shared/Music" folder, and indexing them using the free BluOS music-management app I'd downloaded to my iPad mini.

Almost all the time I had the M50.2 in my system, I used it either as a file player or to stream files from Tidal HiFi, using the NAD's S/PDIF output. (Setting up the M50.2 to access my Tidal account was as simple as entering my username and password in the iPad BluOS app.) The app offers a volume control, but I used the M50.2 set to a fixed output and adjusted playback level with the volume controls on my Ayre Acoustics QX-5 Twenty and PS Audio PerfectWave DirectStream DACs. (The M50.2 also offers choices for equalizing loudness: Track Gain, Album Gain, and Smart Gain.) I used the drive to rip some CDs to WAV or FLAC files—I'm slowly working my way through converting my several thousand CDs to digital files—and experimented with the M50.2's analog inputs (see "Measurements" sidebar).

I found only two operational problems. First, clicking on Info while a track is playing takes you to the Last.fm database, which is not as comprehensive as I would wish. Second, not all the cover art of the albums in my iTunes Music folder had found its way into the NAD's storage. The BluOS app offers a Reload Artwork button in its Settings menu, but this didn't find the missing covers. I suspect that the button is intended to be used when you rip CDs—the discs I ripped with the NAD all had their artwork correctly attached. (When gathering metadata, the M50.2 downloads a checksum for the disc being ripped. The transport will continue to work with a disc until the calculated checksum from the disc matches what's in the metadata.) However, if you subscribe to Last.fm and that database includes the album, you can manually add its missing artwork.

Music
You can choose a file to play by browsing by Artists, Album, Song, Genre, Playlist, or by folder, and with the last you can filter files by Quality: MQA, High Resolution, or CD. Select AutoFill and, in addition to the file being played, all subsequent tracks on the album will be added to the current playlist. I used the M50.2 for several weeks' worth of music enjoyment. Sending data via the S/PDIF connection, using the Esperanto digital datalink from John Marks's new company, worked well with PCM files having sample rates up to 192kHz, with sound quality indistinguishable from my other servers. I'd copied several DSD files to the M50.2's storage, but these didn't show up in the library, though I could find the folders that contained them. I assume that the promised update will allow DSD playback using Roon and a network-connected DAC, though as of October 1, the Roon website notes that while the M50.2 is Roon Ready, it doesn't yet allow playback of MQA files over a network.

Speaking of MQA
The sad death of Tom Petty at the beginning of October had me searching Tidal for Petty's music while I prepared this review, and I found a playlist listed under "Tidal Masters." The "Masters" appellation means that the files are MQA-encoded. Sure enough, when I selected "I Won't Back Down," the metadata indicated that it was an MQA file. I was feeding the NAD's coaxial S/PDIF output to the PS Audio DAC, which won't decode MQA data. However, the M50.2 performed the first "unfolding" of the data, and the PS Audio's screen indicated that it was receiving 24-bit data sampled at 96kHz.

I don't understand the antagonism to MQA expressed by many audiophiles. My own work has shown that the reduction in file size is significant, and my listening comparisons with recordings of known provenance suggest that the improvement in sound quality offered by the proprietary "deblurring" may vary from small to significant, but I have never heard a reduction in sound quality with an MQA-encoded file. And if you don't have an MQA-capable DAC, the fact that a source component like the NAD M50.2 will still give you another octave of ultrasonic information seems to me a useful benefit.

Conclusions
The point of fit'n'forget components like NAD's M50.2 is to enjoy the benefit of computer audio and hi-rez music without having to enter into a complicated and possibly frustrating relationship with a PC. I have been alternating between two such servers for the past couple of years: the Antipodes DX Reference, which I reviewed in October 2015 and control with the iPeng app; and the Aurender N10, which I reviewed in April 2016 and control with Aurender's own Conductor app. Respectively priced at $6950 and up and $7999, these two high-performance server/players cost considerably more than the NAD M50.2. While I wouldn't dare say that a price of $3999 makes the M50.2 a bargain, it's considerably less expensive than the other two products, and offers much the same functionality. Its 2TB storage might be a limitation for those with huge libraries, but its USB ports can be used to connect more storage.

I was impressed by NAD's Masters Series M50.2. It's an easy-to-use, single-box solution to the problems faced in setting up a computer-based audio system.