Digital Processor Reviews

No fewer than eight boxes, powered by six after-market power cables, comprise my current reference front-end (footnote 1). As much as separate boxes can afford superior isolation and provide far more room for visionary engineers to work their magic, the advantages of a single box, which requires a single power cable and far fewer after-market interconnects, are obvious.

Enter Simaudio's Moon 891 network player/preamplifier ($25,000; footnote 2). Also called a "streaming preamplifier"—Simaudio frequently struggles with how to clearly and succinctly brand its Moon products—it includes a DAC that converts PCM and MQA files up to 32/384 (with 24-bit files upconverted to 32-bit) and DSD files up to 256. It also includes what Simaudio company co-owner Costa Koulisakis describes as "a fully configurable" MC/MM phono stage. Both theoretically and practically, it's an ideal solution for someone with space and/or budget constraints.

The 891 is also potentially a good match for the excellent Moon 861 stereo amplifier ($22,000). (I reviewed a bridged pair of 861s last month and used them in this review.) Although the 891 has no internal storage, it can play files from streaming services, a directly attached NAS, or a USB stick. The MiND 2 built into the 891 has a large buffer so caching of content is done during playback to address latency issues, dropouts, and other network instabilities. The buffer is automatically cleared when the 891 is turned off. Its brightness-controlled digital display, which can adapt to the lighting in the listening environment or be turned off completely during playback, is very up to date, with full-color album covers, titles, track names, and volume level visible to this audiophile from 12' away. (It also displays active input and the digital input's sample rate.) Adjustability includes two screen-saver styles, which can be disabled. Firmware updates are easily downloaded and installed from the internet.

The 891 utilizes a uniquely designed remote control, and plays files via phone or pad using the downloadable MiND (Moon Intelligent Network Device) Controller app, which is available for both Android and iOS. To quote the online manual, the app "enables users to stream music from several online services and local network servers, update Moon products automatically, and synchronize playback across devices in multiple Zones simultaneously." It also allows you to create playlists, toggle to and from "standby," switch inputs, and smoothly adjust volume.

Because my system is all-digital—I have no room for a turntable, phono preamplifier, a ton and a half of LPs, and a record cleaner—this review focuses solely on the 891's performance with digital input data. Another reviewer will assess its phono preamp in a Follow-Up.

Diving deeper
In a long email, Koulisakis laid out the rationale behind Moon's North Collection. In edited form, he wrote, "When we set out to design the new top-level Moon Collection which includes the 891 and 861, we came to the realization . . . that combining components in one chassis had the likely potential to surpass the performance of comparable separates. We do, however, continue to believe that the finest performance possible, without cost constraints, still comes from separates. That is why we continue to make our 850P, which remains our finest-ever all-analog preamplifier.

"We also suspected that putting our new finest DAC in the same chassis as the analog preamplifier would yield better results than if we put them in separate boxes. The performance of the 891's preamplifier section is indeed very, very close to the 850P's. However, since the new 800-level quality DAC built into the 891 considerably surpasses the quality of our previous flagship, the 780D v2, the 891's DAC/preamp section does indeed surpass the performance of the 780D v2/850P combination.

"Once the complexities of combining separate functions in one chassis are overcome, the design transcends the limitations of connecting cables and outweighs the penalties of keeping them separate.

"The 891 represents an intricate and sophisticated fusion of analog and digital that is simply not yet possible with separate boxes. Technological advances now allow us to combine multiple components in one box in a way that greatly reduces the limitations caused by proximity to the point where the benefits surpass the penalties. We feel that this holds true at these price levels and will likely hold true at even higher price levels over time."

The 891's MDE-3 DAC architecture, which surpasses the MDE-2 and MDE-1 variants in lower-level Moon components, consists of an FPGA (field programmable gate array), which handles digital input data and clocking. Sayeth Koulisakis, "Timing errors are reduced below the threshold of audibility to the femto-second range (which is 10^–15 power, or a quadrillionth of a second), resulting in superior image focus and detail. Furthermore, each channel uses an eight-channel, 32-bit DAC, with the DAC's eight outputs summed, in a fully balanced configuration per channel. This process is claimed to minimize minute variations between individual DACs and provides a consistent analog signal with less overall distortion and improved inter-channel matching. That translates into better sound clarity. Finally, the DACs themselves are the ESS 9038Pro."

Moon's latest damping technology, the MDB (Moon Damping Base), mounts the analog board on an internal platform that completely disconnects it from the chassis. The audio board is also mounted on a heavy, thermally damped isolation pad that, in Koulisakis's words, "promotes isothermal behavior during heat dissipation that improves inter-channel matching, clarity, focus and accurate harmonics." The MDB includes a special recessed rear panel, also decoupled from the outer chassis, that houses all analog connections. Together, these features are claimed to greatly reduce the unwanted microphonics and related distortions caused by parasitic vibration.

The improved M-Ray2 volume control, an evolved version of the volume control in the flagship 850P, employs 620 fully discrete separate volume settings in steps as fine as 0.1dB, and operates solely in the analog domain. You can change the steps from 0.1dB to 0.5dB in the 891's settings. When you turn the knob fast, increments increase from 0.1 or 0.5dB to a full 1.0dB.

Koulisakis noted that, compared to a mechanical potentiometer, the M-Ray2 volume control is quieter and more precise, with no significant crosstalk and "extremely tight tolerances" between left and right channels. "The volume control has always been a major source of coloration in preamplifiers, which is why we have been using our own electronically controlled fully analog volume control since 1995," he wrote. "The 891 contains the finest volume control system we have ever designed."

The 891's unique remote control communicates via Bluetooth and responds "almost instantly" to changes made on the front panel. It allows you to turn the unit on and off as well as control volume, switch inputs, and adjust balance. The angle of its face purportedly makes it easy to use without lifting it from a tabletop. Without a table in the music room to test this claim, I welcome others to make that call.

Finally, there's the phono section. In addition to basic preset cartridge configurations—the MM mode's is 40dB gain, 47k ohms impedance, and 100pF capacitance, while the MC's is 60dB gain, 100 ohms impedance, and 0pF capacitance—the 891 includes a configurable phono stage whose "advanced mode" permits custom values for gain, impedance, capacitance, and EQ curves (RIAA and IEC). There's also a ground terminal for tonearm grounding. For more on the phono preamp, please see the forthcoming follow-up.

The unit's analog outputs—one pair single-ended and one pair balanced—can be independently set to either "Variable" (for connecting to power amplifiers, subwoofers, and active loudspeakers) or "Fixed" (for headphone amplifiers and other devices with integrated volume controls). The MiND controller app enables you to join multiple MiND zones together to play audio as a cohesive system in multiple rooms simultaneously. Finally, MoonLink technology can trigger automated behavior in multiple Moon devices.

Looking it over
Kudos to Simaudio for the 891's well-composed online manual (footnote 3) and accompanying literature. Minus kudos for the 891's packaging, whose collapsible nature requires two people to hold it together when you pack the baby up. If your unit ever needs servicing, ask your dealer to help send it off or draft your significant other or anyone else you can snare. (Just ask my neighbors about that one.) Unless you love to frustrate yourself and curse loudly, that is.

As someone more averse to regurgitation than cursing, I'll go light on front and back panel contents that are easily assessed online. Besides the display, the attractive two-toned front panel includes a large, smooth-turning volume control and far smaller standby, mute, input, and setup buttons. Their positioning to the left and right of the display is devoid of political connotations. The rear panel's two antennas, six digital inputs (ARC HDMI, AES3, two S/PDIF, and two TosLink optical), 12V trigger out, USB audio, USB host, and two RJ45 network ports are intelligently spaced on the top half of the panel. Below them are the ground terminal, two pairs of single-ended analog inputs, one of which can be used either for line-level signals or phono cartridge outputs and one balanced pair; single pairs of XLR and RCA analog outputs, two ports for Moon's 820S external power supply ($8500—I did not receive one for evaluation; footnote 4), a 50–60Hz three-pronged 15amp IEC inlet, and a power switch.

Once you remove and store the three bolts that unlock the internal isolation platform, read the manual, or learn what to do from your dealer, break the unit in for a good 100 hours, and feed the animals, you're more or less ready to go.

Moving forward
Setup was simple: hoist the not-really-heavy Moon 891 network player/preamplifier onto one of the top shelves of my Grand Prix Monza double rack; set it atop three Wilson Audio Pedestals; connect Ethernet, balanced interconnects, and power cable; flip the rear power switch; depress the front panel's standby button; and enjoy the front panel's short welcome greeting.

First up: Evaluate the 891 on its own. Make a mental note to compare the sound of music streamed from Qobuz or Tidal to the same files played from an attached USB/SSD stick. Also, be sure to evaluate the sound of the same track streamed with the MiND app and with Roon. Finally, be careful not to get so caught up in how enjoyable the sound is that I end up forgetting about all the sonic tests I can possibly perform. As you'll soon read, the last one was the greatest challenge.

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Footnote 1: The very thought of all those boxes and cables will surely drive more than a few of the frequent posters to our website apoplectic.

Footnote 2: See simaudio.com/en/product/891-network-player-preamplifier.

Footnote 3: See simaudio.com/wp-content/uploads/2023/05/20240506-User-Manual-891-En.pdf.

Footnote 4: "It did not occur to me to send you an 820S," Koulisakis wrote after the fact. "The 820S will automatically bypass the 891's built-in MHP supply and provide a blacker background, increased dynamics, and better recovery of the detail responsible for the air and space around instruments. It is not a massive upgrade, but rather a subtle one. The 820S, which can power two units simultaneously, comes with four special 1.5m low-impedance cables; custom lengths are available."