MOON by Simaudio



MOON’s 820S is a specialised, external power supply for reference MOON products 740P preamplifier, 650D and 750D transport-DACs, 780D streaming DAC, and 610LP and 810LP phono stages. A single 820S can be used to power one or two of these models.

By completely isolating the noisy power-generating circuits from those that handle delicate audio signals in the ‘partner product’, 820S will transform the listening experience. The best standalone power supply we have heard? Probably.

This product qualifies for free, remote installation by one of our technicians.

In-store purchase only, please call 0141 221 0221 or email glasgow@loud-clear.co.uk to reserve/enquire.
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The MOON 820S is the large and eagerly anticipated power supply that offers an upgrade path for certain Evolution series models.

Everything Simaudio knows about power supply design with respect to circuit layout, filtration and regulation has gone into the making of 820S. Designed to elevate the performance of products that already perform stratospherically at their price points, the 820S was created through painstaking R&D, creative ingenuity and a passion for perfection.

Featuring state-of-the-art, custom-built dual toroidal transformers, choke filtering and Simaudio’s own MOON Reference Regulation System (M-R2S) circuit, the 820S is capable of doing what was once thought of as virtually impossible: improving on the already superlative power supplies built into our products by further reducing the noise floor while maintaining an even greater voltage stability. The astonishing sheer “blackness” of the musical background created by the addition of this power supply must be heard to be believed.

The 820S is equipped with two sets of outputs. It can upgrade the performance of any one, or any combination of two of the following MOON products simultaneously:

  • 740P Preamplifier
  • 650D, 750D DAC/transports
  • 780D DAC
  • 610LP and 810LP phono preamplifiers

Each output provides DC power for both analogue circuitry (audio) and digital circuitry (controller, CD transport, front panel displays) on 2 separate and unique XLR type cables.

  • Two custom proprietary toroidal transformers with lower magnetic, electrical and thermal loss, for an improved power transfer and a lower regulation factor. The result is increased current speed and better dynamics; one each for analogue and digital power supplies.
  • The analogue and digital power supplies each have 2 special “pi-type” filters after the initial voltage rectification stage that reduce AC transmission noise, using 40,000uF of capacitance (4 x 10,000 uF) and dual choke inductance (2x 20mH).
  • The analogue and digital supplies each have 4 stages of our proprietary M-R2S circuit; A fully discrete voltage regulation circuit using a “precision reference” feeding an amplifier made up of numerous IC’s and transistors as opposed to a single voltage regulation chip. M-R2S outputs pure DC power that is exceptionally fast, very precise, has a virtually unmeasurable noise level, as well as absolute stable voltage.
  • 4-Layer printed circuit boards with pure copper tracings and extremely low impedance characteristics yielding much shorter signal paths and drastically reduced noise levels.
  • Ultra rigid chassis construction to minimize the effects of external vibrations.
  • Accurate matching of the very finest quality electronic components in a symmetrical circuit design.
  • Designed to be powered up at all times for optimal performance.


  • Description: Outboard power-supply upgrade for selected Simaudio Moon Evolution models.
  • Transformers: two, 0.25kVA each.
  • Total capacitance: 80,000µF.
  • Total inductance: 80mH. Output voltages: ±20V (analogue supply, output 1), ±14V (digital supply, output 2).
  • Power consumption at idle: 25W. AC power requirements: 120V/60Hz or 240V/50Hz.
  • Dimensions: 18.75″ (480mm) W by 4″ (103mm) H by 16.81″ (431mm) D. Shipping weight: 40 lbs (18.2kg) shipping.