Music in the Round #77 Page 2

The Multichannel-8's Ethernet interface (gigabit Ethernet only) is used for the playback of computer-based files through a Ravenna ASIO driver at any resolution up to 384kHz, DXD, and DSD256, as well as through up to eight channels. Incoming data are placed in a large memory buffer and clocked by a precision clock. Along with Ravenna's IEEE1588 Precision Time Protocol (PTP), this is intended to eliminate the jitter problems associated with other interfaces. The Multichannel-8 also handles AES/EBU and S/PDIF digital inputs up to 192kHz, and will accept DSD over PCM (DoP).

The case is a low-slung square just under 4" high, with gracefully rounded vertical corners, and is anodized in a satin silver tone. On the left of the front panel, an illuminated MT logo serves as an On/Mute/Off switch and indicator. To the right is engraved "MERGING-NADAC," and past that is a small but eminently communicative digital display. Then comes a large knob that serves as the control for both volume and configuration. At far right are two headphone jacks, one each for 3.5mm and ¼" plugs.

At the center of the NADAC's rear panel is a row of eight balanced analog outputs (three-pin male XLR); below them is a row of eight corresponding unbalanced outputs (RCA). These are merely labeled 1 through 8, not with specific channel names. To their left are clustered input connectors for: Ethernet Ravenna/AES67 (Neutrik EtherCon RJ45 jack), AES/EBU (three-pin female XLR), S/PDIF (TosLink), coaxial (RCA, 44.1–192kHz PCM), and Word Clock (BNC). To the right of the rows of analog outputs are an IEC power inlet, a DC power inlet, and a master power switch.

Physical hookup was easy. I connected the provided Ethernet cable between my gigabit network switch and the Multichannel-8, and the analog outputs to my Audio Research MP1 preamp with Kubala-Sosna Anticipation RCA and XLR interconnects. I installed the MT's ASIO driver on my Baetis XR2 server, and JRiver Media Center recognized the NADAC Multichannel-8 as an output zone. Unfortunately, this didn't work. Merging Technologies' Dominique Brulhart informed me that I needed either to add to my network a managed switch, or to make a direct connection to my server. I chose the latter, and that worked well enough for the ASIO driver panel to see the Multichannel-8, and for the Multichannel 8's display to tell me that it had recognized the server output (footnote 1).

Still no love from the Multichannel-8: It displayed the source name in red, which meant that that source was not connected. Again I contacted Brulhart, who told me of a so-far undocumented NADAC quirk: The only way to make the initial handshake between the Multichannel-8 and the server is to play a file of the precise format (DSD64) displayed, by factory default, on its front panel. (Brulhart said that this glitch—which, I suspect, remained undocumented because MT had expected to resolve it before the NADACs' launch—will soon be corrected.) Indeed, when I played a file of the right format, the handshake succeeded, and everything played brilliantly.

And I mean everything. From 16/44.1 to DXD to DSD256, in mono, stereo, or multichannel, the NADAC Multichannel-8 operated flawlessly. Its buffering inserted one to two seconds of delay in addition to JRiver's latency, but I heard nary a hesitation after the sound began. And even admitting to a positive expectation bias, I was impressed with the sound. A very familiar 24/96 recording, Willie Nelson's Night and Day (DVD-A, Surrounded-By SBE-1001-9; out of print), was presented with a smoothly continuous ambience linking and integrating the instruments, which were distributed among all five loudspeakers surrounding me.

The latest from Manfred Honeck and the Pittsburgh Symphony Orchestra, Beethoven's Symphonies 5 and 7 (SACD/CD, Reference Fresh! FR-718), are dashing performances that conjure reference to Carlos Kleiber's ground-breaking renditions of these works with the Vienna Philharmonic (SACD/CD, Deutsche Grammophon 471 630-2). Via the Multichannel-8, that continuous spatial envelopment spread the PSO widely across the front stage, their sound entirely incorporated into the hall's ambience. Brass sections were almost explosively exuberant in both symphonies, yet remained musically integrated with the rest of the performance, and the dynamic range was staggering. Then, listening to Kleiber's classic readings, I was equally impressed with the Multichannel-8's reproduction—the often edgy sound of these recordings from the mid-1970s was nearly gone, without any loss of clarity or dynamics. Listening sessions with these masterpieces through the NADAC at near-concert levels have been some of my most thrilling listening experiences.

I have some unreleased files that demonstrated that the NADAC Multichannel-8 is on top of some formats still not widely available. Tom Caulfield, a Grammy-winning recording engineer who has worked for Channel Classics and other labels, recently sent me a multichannel DSD256 file from a session with Color Field, a group comprising musicians of the Chicago Lyric Opera and the Chicago Symphony, for a recording of James Matheson's String Quartet, to be released this year on Yarlung Records. The opening notes were startling—I had the disturbing but exhilarating feeling that music was actually being made in my room, not merely reproduced. The sound was no more "multichannel" than it was "stereo"—the four players seemed almost within reach, and my room seemed to expand around me. Caulfield had included a few photos of the session, held at the Segerstrom Center, in Costa Mesa, California. When I looked at them—by George, that's exactly what I'd heard. Not only was I completely transfixed: I kept thinking, If others could only hear this, hi-rez multichannel music would take off.

I did also hear and appreciate some great and transparent two-channel sound with the Multichannel-8 in stereo mode, both from my Bowers & Wilkins 800 Diamond speakers as well through a pair of Bowers & Wilkins P5 headphones. I was also able to compare the NADAC directly with the exaSound e28 by setting JRiver to link the two DACs' outputs and switching my preamp between them. That was maddening—in quick A/B comparisons, they were indistinguishable. However, after I'd listened to one DAC for half an hour or so, a switch to the other could reveal some very tiny differences. Consistently, the e28 had a bit more bass and a slightly more forward sound. The NADAC's bass was excellent but less emphatic, and the front of its soundstage was barely more distant. Those minuscule differences might aid those who can afford either in choosing between them, but they didn't help me (footnote 2).

Still, I found the NADAC Multichannel-8 flawless. It provided some of the best sound I have ever heard in my home. With Merging Technologies' Ravenna-based network linkage, multiple NADACs can operate independently in different zones without requiring additional wiring or less-reliable wireless connections. I can't see any reason why one would not choose the NADAC Multichannel-8 for a modern multichannel or two-channel system.

Theta Digital Dreadnaught D multichannel power amplifier
For years now, class-D amplifiers have been encroaching on the mainstream of high-end audio. The first onslaught were based on the TriPath technology—it was pretty good, but burdened with a dim, opaque treble. That was largely erased by the second wave of class-D amplification, based on Bang & Olufsen's ICEpower technology, but still, the gap between those amps and the very best analog power amps was audible to most of us. Theta Digital showed the two-channel Dreadnaught D class-D amplifier ($6149.95) at the 2015 Consumer Electronics Show, but I wasn't greatly interested in it—until I experienced a revelatory demonstration of Bruno Putzeys' Mola Mola power amp, based on his Hypex NCore technology. Shortly thereafter, I enjoyed reading Larry Greenhill's glowing review of Theta's Prometheus monoblock ($12,000/pair), which uses the NCore module, as well as John Atkinson's bench tests of it. I also noted the appearance of a number of other amps based on class-D, such as NAD's Masters Series M22, reviewed elsewhere in this issue. I guess this is the third wave.

The Dreadnaught's D designation no doubt indicates class-D, but it's also the fourth model of the Dreadnaught series. Like its predecessors, it's a configurable design with a fixed power supply and one or more individual amplifier modules. In fact, the Dreadnaught D has two independent power supplies, each requiring its own power cord, and each supporting two of its four amp-module slots. Each supply consists of a 1.18kVA toroidal transformer, 40,000µF of power-supply reservoir capacitance per slot, and two 30A rectifiers per slot (footnote 3). Any of three module options can be chosen, each based on the same NC1200 Hypex boards used in the Prometheus: mono 225W, stereo 225Wpc, or mono (bridged) 500W operation. Up to eight channels of 225W each are possible. After I had extended discussions with Theta, they recommended a 225Wx3 configuration for me, but sent what was available for review purposes: a 225Wx5 unit ($8699.95).

My first impression of the Dreadnaught D was of a traditionally big and heavy power amp: It measures 17.5" wide by 7.9" high by 19.6" deep, and weighs 98.6 lbs "fully loaded." Hey, wasn't class-D supposed to give us more efficient designs that were smaller and lighter? But Theta's philosophy is that switched-mode power supplies, even Hypex's, are incompatible with efficiency or instantaneous power. To quote Jeff Hipps of ATI (Theta's parent company): "Switch mode supplies are typically fully regulated which limits headroom, are less reliable (more parts), must be filtered to remove the switching noise and have issues we call 'power over time'—where the power supply cannot supply full current if it is demanded for more than a few seconds."

On the rear panel, the butt end of each amp module sports selectable balanced (XLR) and single-ended (RCA) inputs, and a pair of substantial multiway speaker terminals. On the impressively massive front panel is an LED to indicate protection mode (it never lit up), and a three-color LED to indicate status (Standby/Warming Up/On). I used the XLR inputs, and connected my three front Bowers & Wilkins 800 Diamond speakers to three of the five amp modules. I then plugged each of the two power supplies into the wall, turned on each one using its separate switch on the rear, then pressed the front-panel power button. After a few seconds of warmup, this button gleamed blue and the sound bloomed.

Y'know, some folks in this hobby believe that all amps, when used appropriately, sound the same. I find that impossible to accept. Every amplifier I have on hand is a really good amp that, on its own, is more than capable of providing more-than-satisfying sound. Yet, in direct comparisons, each reveals a character that subtly distinguishes it from the others. When I listen to music, is one of these amps right and all the others wrong? If I didn't make the recording and/or wasn't present at the performance, how can I know?

What I can say is that Theta Digital's Dreadnaught D not only sounded good, it sounded right. I could—and in my next column, I will—pick away at the things that distinguish it from other amps. But from the moment I turned it on, I've been smiling. The Dreadnaught D is really quiet and very dynamic, and sounds consistent at any output level. And there's nothing about its sound that says "digital"—even though all my sources are.

I'll have more to say about the Dreadnaught D after we've lived together for a couple more months. But for now, "Louie, I think this is the beginning of a beautiful friendship."

Footnote 1: Because I used a direct connection to my streamer, my home network and iPad didn't see the NADAC Multichannel-8. To sample the NADAC's iOS app, I ran a 40' AudioQuest Ethernet cable from the Multichannel-8 to my main router, in the next room. The app duplicates the front-panel controls. Some users might find that convenient, especially if the NADAC isn't in the listening room—but aside from the volume control, I found the NADAC to be a set-and-forget device: I didn't need a remote control.

Footnote 2: exaSound has just released their PlayPoint Network Audio Player, which will endow their DACs, including the e28, with network streaming abilities. The PlayPoint's feature set differs from the NADAC's, and it doesn't use AES67 AoIP. I'll report on it in my May column.

Footnote 3: These specifications aren't too different from those of the Prometheus's potent power supply: 1.44kVA toroid, 20,000µF capacitance, and two 30A rectifiers.


PaulMG's picture

It seems that finally class-D technology can outperform low efficient class-A circuit designs. That would be a real innovation compared to mere pseudo-innovations or chassis-styling 'innovations' for amplifier designs. How would you classify the Equibit technology introduced by TacT Audio in their Millenium amplifier. Is the topology comparable with Ncore?

Kal Rubinson's picture

I have not used an Equibit-based amp although it has been around for almost 2 decades. Stereophile has some older reports posted on this site.

Frans's picture

Interesting approach. I too have a host of these terrible little wall warts and I have taken to using short pigtail extensions to plugging multiples into the same 6-outlet wall socket because they would never fit together. I end up with a droopy mess... What I really need is a single device that replaces multiple wall warts (switchable voltage per device). Then add the lower noise and other benefits and I would be highly interested. As such there is little incentive to do this one at a time except for very specific devices.

IgAK's picture


No need to "suspect them of plotting revolt"...because if you are using switchers, your noise floor is already under attack and it is too late for suspicion. While iFi's superior filtering is apparently working to your benefit as per your results, that is only half the story. There's the noise switchers output on the cable, and there's the RF noise they broadcast like a radio station directly to all your components nearby them. How sensitive or shielded those components are and how much a particular switching wart puts out as over the air RF varies but we certainly know that RF just is not a good thing around audio! Always best to just keep switching warts well away from your system, and the cheap generics in particular. This is a problem that linear supplies and battery ones just do not have, one of their advantages. Getting "switched" tends to leave bruises, maybe not quite like getting "caned", but not good for your listening experience, anyway.

IgAK's picture

...for a new style of power strip/filter/conditioner. One that is a shielding box with widely spaced outlets *inside* to specifically accommodate wall warts, and a small aperture for leading out the output wires. Add Ferrites to the aperture lip for automatic output RF filtering. Filter the incoming power, of course - not so much for the warts as to keep their grunge out of the house power. Should be long and narrow to best fit behind one's equipment. Preferably not astronomically priced. Wall warts are an unavoidable fact of audiophile life nowadays so I suspect that pretty much everyone can benefit from such an item.

Ok, I've spelled out the basic design, and it is not one I am set up to manufacture among my other items that I do. Any one watching these comments that can take up a good idea and run with it?


techdiy's picture

A dozen years ago Linear Technologies introduced their line of quiet switching regulators -- unlike conventional switching supply methodologies these "switch" through the linear portion of the conduction curve, rather than quickly transitioning to saturation. (Controlled slew rate switching) It is the very rapid di/dt of conventional switching regulators which causes spikes of radiated energy. Take a look at the LT3439 data sheet.

marcelk's picture

Kal, thanks for the insightful review.

One thing that I'm curious about: how does this DAC compare to a Merging Hapi with the DA8P card (with some DB25-to-XLR cables thrown in)? I understand that the case looks very different, but it would be interesting how the two match up sonically.