The 404 Reference integrated amplifier

Following the runaway success of The Moonriver Model 404 (Standard), we decided to move a step further by improving on the already excellent design platform of the Standard 404 model. The Moonriver Model 404 Reference achieves even better performance over the Standard Model, while retaining a sensible price point.

Just like the Standard Model 404, the 404 Reference amplifier will extract hidden elements, and render textures from within any audio format; but with the capability to drive any speaker on the market – despite its moderate power. Only the source, speakers and room will set the performance limit. Its culture will suit all music, as the Model 404 is by design, set to define the faintest nuances of which tonal integrity is composed.

The power supply section has been improved to the maximum. The 404 standard uses a total of 57000uf capacitance. The 404 Reference lifts the capacitance to a spectacular 107000uf of which 21000 of them are reserved for the preamp only. This enormous increment expands the driving behaviour; the dynamic character; digs out more detail; low level information; a deeper and more articulate soundtstage; space between instruments is vast, while the bass has greater authority and is more confident than ever before.

The texture of each individual instrument is exposed exponentially in comparison with the Standard version. A fully discrete preamp section serves to provide acute dynamic awareness, while a high output stage that is custom-optimised for bandwidth and distortion, gives neutral character and transient fidelity. A sophisticated selection of components fuses the design against tonal traits, therefore preserving naturalness throughout the shortest feasible signal path.

Furthermore, an integrated phono stage, USB DAC, (two) preamp outputs and a tape monitor loop expand functionality to form an ideally flexible integrated amplifier.

Design & Ergonomics

We had a very clear vision when we conceived the Moonriver 404 amplifier: Classic design with a modern touch; high quality materials such as massive aluminum knobs, solid walnut cheeks, sturdy enclosure; ergonomic user interface.

There are no “shaved” aesthetics here, no display with complicated serial menus and hidden functions, nor a single multi-function knob for “minimalistic” purposes.
The heart of Model 404 is pure and minimal but the interface is user oriented and easy to operate by anyone in seconds with no need to resort to the user manual. Four knobs and three switches give direct access to any function.

Modular Architecture

Moonriver 404 amplifier is modular by nature; it can accommodate an MM or MM/MC phono stage and a USB asynchronous DAC. Fitting these modules is simple and can take place at any time, on or after purchase. The USB DAC may also be upgraded with a newer version to meet future needs.

You may find this feature to be vanishingly scarce in audiophile products as a result of today’s “minimalist” design mentality and the various myths accompanying it. However, balance control addresses a common problem; speakers that are positioned in asymmetry, in a non-balanced room environment. It thus provides the simplest tweak towards achieving a proper sound stage.

Living rooms and house furniture are meant to serve everyday life and may not be provisioned with an ideal listening spot, evenly distanced from each speaker to form an equilateral triangle. It is also not uncommon for one speaker to have to be placed nearer room boundaries than the other, having various frequencies boosted in a more or less predictable pattern. More often than not, balance control would come in handy in that it drastically helps overcoming volume level unevenness and in some cases even reclaiming stereo effect and the resulting focused sound stage.

As expected, the way balance control is implemented on the Moonriver 404 amplifier, in parallel, will not degrade or affect the signal in any way determinable.

Model 404 incorporates no less than 5 separate power supplies, each featuring overload protection. The power amplifier specifically runs on a dual mono configuration, beginning from separate windings on the toroidal transformer.

Signal switches are implemented via relays, while volume attenuation is trusted on the legendary blue ALPS pot.

A soft start circuit based on a 30A relay ensures that even the on/off switch is thought out to work with virtually no burden or wear for decades.

Components are carefully selected for both suitability and reliability. We make no use of surface-mount in analog circuits, despite the fact that through-hole costs more and requires advanced space management & layout strategies.

Each element utilized has to be of proven stability and sustained higher performance -proficient implementation provided- before making it into our analog paths.

As for the sound, we are not to say whether Model 404 is virtually transparent or inherently forgiving. Voicing it to appreciate the playlist and respect the user at all times has been the sum of all of our effort; a sincere effort to achieve effortlessness.

Verdict: Very simply I am conservatively rating this component as the best solid state integrated amplifier I have ever auditioned.  In that respect it is something of a world wonder.

This amplifier has four core characteristics. It’s ability to render true tones is breathtaking. It’s handling of dynamics is superb. The bass response is deep and accurate. And finally, it organizes the sound field in an almost incomparable fashion.

I have no hesitation at all in awarding it a ‘Wall of Sound Gold Star’. I suggest solid state enthusiasts run and not walk to their nearest Moonriver dealer to check it out.

Technical

• Inputs: 5 (line 1 and 4 optionally occupied by phono stage and USB DAC respectively, 1 x tape loop)
• Outputs: 2 x preamp out, 1 x rec out
• Max output power: 50 W / channel into 8 Ω
• Frequency response: 10 Hz to 50 kHz
• Total harmonic distortion: 0.05%
• Signal to noise ratio: 85 dB (line)
• Idle Consumption: 22 Watts
• Dimensions (mm): 430 (W) x 390 (D) x 135 (H)
• Weight: 13 kg