The NADAC ST-2 is Swiss-company Merging Technologies’ first foray into consumer electronics. However, Merging Technologies is hardly a newbie -- their reputation in professional audio is that of legend.
Merging Technologies was founded 25 years ago by Claude Cellier, who’d previously worked with electronics maker Nagra, another Swiss company with a rich history in pro audio -- namely in various types of recorders -- that then ventured into high-end home audio. Though probably best known for their Pyramix professional audio workstation, Merging has recently ventured far into networked audio interfaces with their Horus and Hapi products. It was the experience gained in designing the Horus and Hapi models that convinced Merging to launch the two-channel Networked Attached Digital-to-Analog Converter (NADAC) ST-2; an eight-channel version, the NADAC MC-8, is also available.
As for the NADAC’s networking capability, it uses the Ravenna/AES67 protocol, also used in the Horus and Hapi products. Merging describes Ravenna as follows: “This open and published IP network technology had been created to meet the demands of national broadcasters and focused on essential requirements of extremely accurate clocking, high resistance to packet loss and very low latency.” Merging says that they “worked closely with the developers” of Ravenna to allow the software to accommodate high-resolution PCM and DSD content, which would of course be a requirement for a high-end home-audio DAC in 2016. The NADAC ST-2 retails for $10,500 USD.
Features and operation
The Merging NADAC ST-2 has all the features of a typical high-end DAC. Its digital inputs include AES/EBU on a three-pin XLR connector (compatible with PCM resolutions of 44.1 to 192kHz), S/PDIF optical using a TosLink connector (44.1-96kHz PCM), and S/PDIF coaxial using an RCA connector (44.1-96kHz PCM). Analog outputs are stereo pairs of RCA and XLR connectors.
What sets the NADAC apart is its Ethernet RJ45 EtherCon connection, which permits cable runs of up to 100m. Through this input the NADAC can accept 44.1-384kHz PCM, DXD, and DSD64/128/256. This connection is claimed to be asynchronous, meaning that the NADAC controls the rate at which digital data are sent from the computer to the DAC. Of course, you can easily find USB implementations that permit asynchronous hi-rez PCM and DSD transmission, though not with nearly the cable lengths offered by the NADAC. The Ravenna protocol allows the NADAC to interface with your computer using the Ravenna Audio Stream Input/Output (ASIO) driver for Windows, or the Ravenna Core Audio driver for Mac OS X (both are downloadable from Merging’s website). One of Ravenna’s advantages is said to be ultraprecise clocking of the digital input using its Precision Time Protocol feature; Merging specifies for the ST-2 a clock resolution of one nanosecond. Other rear-panel connections include a word-clock input using a BNC connector, and an IEC power-cord inlet.
The NADAC ST-2 measures 17”W x 3.7”H x 17”D and weighs 24.2 pounds. Its silver-anodized aluminum case has rounded corners, and its top panel -- secured by four large screws, one in each corner -- is recessed to give it a clean appearance. In the right half of the front panel is a 160x128 OLED display, to the right of which is a knob that’s alternately used to control the volume and to access and navigate the menu system. A short press of this knob takes you to the functions most frequently used, such as source selection or switching between the main and headphone outputs. A longer press brings up other functions, such as digital filter selection (Sharp or Slow; I mainly used Slow). Farther right are two headphone jacks (3.5mm and 6mm). The maximum output level of the NADAC’s headphone amplifier is 4V RMS, with a claimed dynamic range of 123dBA. One potentially helpful feature is that the NADAC’s headphone and main outputs can be used simultaneously with different sources, and set to different volumes. The OLED screen prominently displays the volume setting and, in smaller characters, the sampling rate, the digital input selected, and whether you’re adjusting the headphone or main outputs.
The NADAC ST-2 can be controlled in a variety of ways. As mentioned above, the menu system lets the user choose inputs, including the computer sources available on the network. You can also download, from Apple’s App Store, the free NADAC iOS app, to use your iPad or iPhone to adjust volume and select sources. (I used my iPhone 6.) Additional features on the app are the ability to mute the NADAC’s output and trim each channel (this can also be used as a balance control). The default display, both on the app and the NADAC’s front panel, is the volume level, in 99 steps.
The NADAC ST-2 uses the ESS Sabre ES9008S DAC chip, an eight-channel device that, when implemented in a stereo configuration, yields what Merging says is “improved linearity, greater dynamic range and a lower noise floor.” The specified dynamic range is 130dB through the balanced outputs, which I used exclusively. The maximum output level of 6.1V RMS should ensure that the NADAC will drive any power amplifier to its full potential.
Setup and use
I used the NADAC ST-2 in a variety of ways. I alternated connecting the TosLink and coaxial outputs of my Oppo Digital BDP-103 universal Blu-ray player. Using Oppo’s Media Control app, I fed the NADAC files from: my 1TB external hard drive, which is linked to the Oppo BD via USB; the integrated Tidal music-streaming service (the Oppo is connected to my network); and a USB stick plugged into the Oppo’s front-panel USB port. From the Merging NADAC Support page, I also downloaded the Ravenna Core Audio driver to my Apple MacBook Air laptop computer. That done, I connected the MacBook to the NADAC with a Thunderbolt-to-Ethernet adapter and Ethernet cable. Immediately, “jeffreys-macbook-air” appeared on the NADAC’s Source screen. I selected it, chose the NADAC for sound output in my MacBook’s Audio MIDI Setup, and started iTunes or JRiver Media Center 21 (I tried both to make sure they worked, but mainly used JRiver). Of course, using the Ravenna protocol, it would be possible to choose additional sources on the network, such as additional computers. I had only the one.
The first recording I listened to was soloist Rachel Podger and Arte dei Suonatori performing the Allegro of Vivaldi’s Violin Concerto in G Major, Op.4 No.3, recorded in 2003 in the Church of the High Catholic Seminary, in Poland (DSD64, Channel Classics). This spirited, well-received performance was reproduced by the NADAC with a full, dense palette of tonal colors -- the sound was very lively. The NADAC amply displayed the rhythmic intensity of Vivaldi’s writing, and made this track sound quite vivid, with uncommonly “solid” images. In fact, the NADAC did wonders with this track: Podger’s instrument sounded like no mere facsimile of a violin. Instead, the sounds of the strings were so tangible that I felt I could reach out and wrap my hand around them. The highest frequencies were delicately rendered and sounded completely natural -- the antithesis of early digital. There were no hard edges, no overly crisp transients -- just beautiful sound. The overall sound was very composed and balanced, while still letting the rhythmic, driving energy of this performance shine through unaltered.
On their 2002 release The Gentlemen of the Chapel Royal, the Gents, an all-male Dutch vocal ensemble, are conducted by Peter Dijkstra and accompanied by the Diapente Viol Consort (DSD64, Channel Classics). Their performance of “Ave Maria” was ethereal. The sense of space around the singers, the extreme depth of soundfield, and the tonally meaty voices made this track super-enjoyable through the NADAC ST-2. This choral work, and the Vivaldi before it, made me appreciate how tangibly real music can sound when reproduced by a great audio component; by comparison, some DACs sound more translucent, which can produce an exaggerated sense of air and detail. Through the NADAC, the music was just more solidly, more tangibly reproduced. It was tantamount to the difference between crayon and paint.
The NADAC ST-2 didn’t bang me over the head with obviously “hi-rez” sound. Many recent high-end DACs seem voiced in just that fashion, perhaps to mimic the specs race that’s obviously on. This between-the-hashmarks sound, instead of highlighting the frequency extremes, made the NADAC’s reproduction of most music completely approachable, and one that I think many audiophiles will cotton to.
High-resolution PCM faired just as well as the many DSD tracks I played. I listened to Robert Plant and Alison Krauss sing “Please Read the Letter,” from their Raising Sand (24-bit/96kHz AIFF, Rounder), and was mesmerized by the solidity of the drum kit. It wasn’t so much more bass depth or more impact or anything like that. Instead, the sound was defined by the authenticity of the initial stroke -- I could really feel the amount of tension on the skin -- and the easily perceptible decay after each stroke. If you’re getting the sense that the NADAC was easy to listen to, you’re right.
The intensity of percussion instruments carried over to CD-resolution music. The first drumstroke about three seconds into “Stone,” from Alessia Cara’s Know It All (16/44.1 FLAC, Def Jam/Tidal), even at a moderate volume level of barely 75dB, was solid beyond anything I’ve heard from any other DAC I’ve had in my system. Those qualities -- solidity of images, density of tonal colors -- were present in all the music I played through the NADAC.
In fact, this theme defined the product for my ears. Some DACs scream resolution, particularly at the upper-frequency extremes. The NADAC didn’t have that signature, though it certainly reproduced fine detail. The real action with the NADAC was what happened from the upper midrange down to the bass. The most apt comparison I can think is this: have you ever heard a speaker system that has great low bass, but no real punch in the midbass? Music reproduced by such a speaker is never fully satisfying. Well, the NADAC best shone where the music lives -- in the midbass and midrange. The net result was that I simply enjoyed my recordings, even if I didn’t marvel at their extreme resolution.
I compared the Merging NADAC ST-2 to Wadia Digital’s di322 DAC, which, at $3500, is a giant killer. As I moved the Wadia into place beside the Merging, it was striking just how alike they looked: the rounded corners, the inset top panels, even the colors of the anodized aluminum -- all were very similar. The NADAC is built commensurate with its price -- which is to say, on a par with other ca.-$10,000 DACs I’ve seen. The Wadia, however, is built just as well, and is even a touch heavier. I’ve never seen a sub-$5000 DAC better built than the di322. In terms of functionality, both models accept up to DSD256 and PCM up to 384kHz, courtesy of Sabre DACs: the ES9016S in the Wadia, the ES9008S in the Merging. One functional difference in favor of the Wadia is that it will accept up to 192kHz through its TosLink and coax inputs, whereas the NADAC ST-2 is limited to 96kHz through these connectors.
The biggest functional difference is the Merging’s network connection. The Wadia has a USB input to interface with your computer, a method we’re almost all familiar with by now. The NADAC has an Ethernet connection and adds the ability to connect to your home network, opening up myriad possibilities in terms of computer source selection and control via Web-based applications. I found both to operate flawlessly, though the biggest ergonomic difference is that the Wadia comes with a small metal remote control that I really like; if you prefer to use your smartphone as your remote, the Merging has you covered. But I wish the NADAC came with a remote, or that Merging offered one as an option. Call me old school.
I compared the Wadia and Merging using their coaxial inputs, alternately connected to my Oppo BDP-103. I made sure levels were matched with the SPL meter on my iPhone 6, and away I went. First up was “North Dakota,” from Lyle Lovett’s Joshua Judges Ruth (16/44.1 FLAC, MCA/Tidal). Through the NADAC, Lovett’s voice was . . . dense: my notes say “no holes, tonally solid.” The noise floor was super low, and the resolution of fine detail -- the piano was beautifully rendered -- was superb. Switching to the Wadia di322, the first thing I noticed was that Lovett’s voice sounded a touch more wispy, not as tonally dense. This altogether lighter sound wasn’t as substantial as what I heard through the NADAC. The piano, again, didn’t have quite the concentrated intensity through the Wadia that it so amply displayed through the Merging DAC. Perhaps as a result, high-frequency detail was a touch more obvious through the Wadia, though the drums were just as impactful.
Next up was “The Forge of Angels,” from Enya’s Dark Sky Island (16/44.1 FLAC, Warner Bros./Tidal). The NADAC fully unleashed this track’s power and weight. The soundstage was huge, and the music was delivered with a physicality I could feel in my chest. At the same time, again, the noise floor was low, the music springing from a backdrop so silent that this track’s first note startled me when it leaped from the speakers. The Wadia was almost as startling with Enya, but it lacked the tonal density, and therefore the foundation, provided by the Merging. At the time, I wondered if the differences would be as easily heard through small bookshelf loudspeakers. Either way, through the full-range Rockport Technologies Cygnus speakers I was using, the sound of the Enya track through the NADAC was tonally impenetrable and -- especially through the lower midrange -- downright sturdier, with more heft and ease. The Wadia was more treble-centric, just as it had been with the Lovett track. I was surprised by these results, having written in my review of the Wadia that “Its sound was full, big, and played deep -- deep bass, deep soundstage, wide dynamic range. It relished music that I like to play at high volumes with fist-pumping verve.”
Ultimately -- and perhaps not surprisingly, considering the price difference -- I preferred the sound of the Merging NADAC ST-2. Its tonally dense sound made music more realistic, more emotionally powerful, and sometimes even more cozy, depending on the selection.
The Merging NADAC ST-2 is a welcome addition to the high-end DAC scene. It has a lot going for it. First, the price: no, it’s not another $5000 DAC, a price point so popular these days. But for twice that you get a Swiss-made product from a company that has a rich history in the making of music. It’s a full-size DAC with a full-size sound. It operates as advertised, throughout its many input and control options. Considering all that it does and is, I think it easily justifies its price of $10,500.
In terms of features, the NADAC is a next-generation device, replacing the USB connection that has become the standard way to connect a DAC to a computer system. Instead, the NADAC’s Ethernet port, implemented in conjunction with an industry-standard software protocol (Ravenna), delivers network capability so that the NADAC can access music from a variety of computer-derived sources throughout the user’s home. This functionality should easily become the new standard; I think it will replace USB as the de facto method for connecting computer devices to an audio system. It works great.
Finally, the Merging NADAC ST-2 sounds superb. Its full, complete sound is never objectionable, and never comes across as overly “hi-fi.” Yes, it sounds natural. And yes, it has excellent detail and resolution, including low noise. But it won’t make all the audiophile alarms go off in your head -- and that’s a good thing. Over the weeks I had the NADAC ST-2 in my system, it made me want to listen to music, not assess sound quality.
In terms of value, functionality, and sound quality, this Swiss-made DAC will win many fans. I predict that it will enjoy a long run in a product category that seems to change daily.
. . . Jeff Fritz
- Speakers -- Magico Q7 Mk II, Rockport Technologies Cygnus
- Amplifier -- Soulution 711
- Sources -- Apple MacBook Air running OS 10.10.5, iTunes, JRiver Media Center 21; Wadia di322 DAC; Oppo Digital BDP-103 universal Blu-ray player with Tidal streaming and 1TB hard drive accessed through Oppo’s Media Control app
- Cables -- Nordost Valhalla interconnects, speaker cables, power cords
Merging NADAC ST-2 Digital-to-Analog Converter
Price: $10,500 USD.
Warranty: Three years parts and labor.
Route du Verney 4
Phone: +41 21 946 04 44
North American distributor:
On a Higher Note
PO Box 698
San Juan Capistrano, CA 92693
Phone: (949) 544-1990