Simaudio Moon Evolution 880M monoblock power amplifier

In the September 2005 issue (Vol.28 No.9), I reviewed Simaudio's first reference-quality power amplifier: the 1000W, 220-lb Moon Rock monoblock ($37,000/pair). At the time, the Rock was a dramatic departure for Simaudio, then primarily known as a maker of midpriced gear that was good for the money. I found a lot to like about the Rock, concluding that while it wasn't quite up to the standard of the best superamps of the time, it was very good—and, for Simaudio, an admirable first shot at the state of the art.

Since that time, Simaudio has launched and filled out its Moon Evolution line, in the process moving steadily upmarket. That Simaudio has taken that move seriously has been proven by such Moon Evolution models as the Andromeda CD player, the P-8 preamp, and the W-8 power amp, which have set new performance standards and won rave reviews. The Moon line kept growing and getting stronger, leaving only one thing missing: a big-time, big-power, big-money, big-everything reference power amplifier. And in January 2011, that void was filled by the . . .

Moon Evolution 880M
Unlike the Moon Rock, the product of a very short development cycle to service an urgent market niche, the Moon Evolution 880M was developed and refined over a period of years, according to Simaudio's Lionel Goodfield. "Don't get me wrong," he told me; "the Rocks were good amps in spite of the short development time . . . we've got really good engineers. But we spent years perfecting the 880Ms. They really show what we can do."

The 880M is based on principles and circuitry similar to those seen in Simaudio's smaller Moon Evolution amps, here scaled up to such numbers as: 32 output devices (Moon bipolar transistors custom-made to Simaudio's specs), 260,000µF of power-supply capacitance, maximum outputs of 80V and 100A, and, of course, power outputs of 800W into 8 ohms or 1600W into 4 ohms. The rest of the 880M's specs are equally impressive—including a shipping weight of 92 lbs. Each amp is packaged in a heavy-duty flight case, which makes handling and unpacking it much easier than having to power-lift it out of a deep cardboard box.

The 880M is a DC-coupled, fully balanced differential design, and its long incubation in R&D allowed Simaudio to develop and include several new technical features. The circuitry of each 880M begins with a massive power supply built on two 1.3kVA toroidal transformers, a proprietary design unique to Moon, and two banks of soda-can–sized capacitors. Then comes a proprietary combination of topography and components that Simaudio calls its Lynx Technology, whose key features include the absence of any global feedback, no input or output coupling capacitors, short circuit paths, and the creation of an optimal electromagnetic and physical environment for each component. For example, they use four-layer circuit boards with heavy traces of pure copper, not to assign certain functions to particular layers, but to minimize the length of the signal path and ensure that the two sides of the balanced circuit are identical.


The components themselves are custom-made to Simaudio's exacting specs or, in the case of COTS (Commercial Off-The-Shelf ) parts, top-quality, these are rigorously screened, and hand-matched to ensure consistency from side to side and from amp to amp. The 880M's slew rate is given as 70V/µsec, and even at 800W of output, Simaudio claims total harmonic distortion (THD) of less than 0.04%. John Atkinson's measurements will tell the tale, but these are impressive claims for a megawatt amp with no global negative feedback.

Even more impressive was how effortlessly the 880Ms delivered this performance—after long listening sessions at higher-than-normal levels, they were barely warm to the touch. According to Simaudio, the 880M run in class-A up to 10W, and thereafter in class-AB to its rated output. Simaudio believes that this approach provides the optimal mix of all-out performance and efficiency, and ensures long, trouble-free life by maintaining each amp's components in a cool, thermally stable environment and running them at only a tiny fraction of their rated capacity.

The 880M is physically impressive as well. Although substantial, it's not all that big—but it's Solid with a capital S. Its appearance mirrors those of other Moon Evolution components, with a richly finished case of black-anodized aluminum, and a heavy front panel comprising elegantly curved extrusions of brushed aluminum flanking a black or silver center section. Like the other Moon Evolutions, the 880M is made stable and mechanically grounded by the chassis itself and its precisely positioned, conical feet of hardened steel. Thankfully, small, indented steel pucks are also provided; slip these under the cones to prevent them from impaling your floor or equipment stand.

Comparisons from the Present
The Moon Evolution 880M is impressive in terms of technology, specs, design, and workmanship, but the true test of any component is how well it performs when the stylus hits the groove.

After a suitable amount of break-in, during which the amps remained powered up per Simaudio's instructions, I sat down to get a handle on what the 880Ms were and weren't doing in my system. I cued up Georg Solti and Chicago Symphony and Chorus's first recording, from 1972, of Beethoven's Symphony 9 (LP, London CSP-8), one of my "Records To Die For" for this year, which had been spending a lot of time on my turntable.

The first thing that got my attention was how different the 880Ms sounded from the VTL Ichibans and Mark Levinson No.20.6s, both of which I've been using for many years. I know those amps' limitations very well, and am willing to accept them because both are true to the music. Although dramatically different in format and technology, the VTLs and Levinsons—as well as most other top-shelf amps I've heard—provide a similar perspective on a performance.

It surprised me that the 880M's perspective was so different. Having just begun my listening, I wasn't yet prepared to say that it was better or worse, just . . . different. The first thing I noticed was that choristers in the final movement, instruments lower in the mix, the second and third chairs—all the lesser elements of the music—were much more apparent and contributed more to the performance, through the Simaudio. Conversely, first chairs, soloists, and strong melody lines were less prominent. If it hadn't been the same LP of the same recording, I might have suspected that I was listening to two different mixes of the same performance/recording. Whenever I switched from the 880Ms back to the VTLs or Levinsons, it sounded as if spot mikes had been added. The perspective still sounded natural, but different. Those second- and third-chair players, presented so clearly through the 880Ms, commanded much less of my attention.

My first impression was that the 880Ms' soundstage was foreshortened, its leading edge farther back than the other amps', and the rear of its stage more forward. The Levinsons produced a soundstage that was more recessed overall, but seemed deeper. The VTLs created a stage that projected farther forward than did the 880Ms, and had a beguiling way of floating those soloists and lead parts on a cushion of air at the front of the stage. The more I listened, however, the more I was struck by the consistency and stability of the 880Ms' soundstage. The VTLs' open, airy, forward projection and the Levinsons' depth began to seem slightly inconsistent, varying with the musical content and flow. Compared to the 880Ms' unwavering stability, the images projected at the front of the VTLs' stage, or the information at the very back of the Levinsons' stage, seemed to float at times, as if it were only tenuously connected to the rest of the soundstage. Plus, the rear corners of their stages would contract inward at times, matching the 880Ms' performance only at climaxes, when the sheer power of the music would push the rear corners outward; and during the softest passages, when the low-level reflections that defined the side and rear walls of the recording venue would be apparent. There was none of this variability with the 880Ms—the stage was always the same wide, deep, solid, coherent portrayal of the original recording space.

Individual instruments and voices within the 880Ms' soundstage had realistic, tangible body. Midway through Act 2 of Alain Lombard and the Paris Opéra Comique's recording of Delibes's Lakmé (LP, Seraphim SIC-6082), shortly after the beginning of side 4, Gerald (Charles Burles) enters and begins a duet with Lakmé (Mady Mesplé). It's one of my favorite scenes in the opera, and one I often use to evaluate how well a component reproduces the details and subtleties that give an image its realistic feel. When a component gets it right, Burles's presence is startling—it feels as if he's in the room with me. The 880Ms passed this test with flying colors, giving Burles a holographic three-dimensionality. Here, too, the 880Ms' sound was more consistent than the other amps', drawing my attention away from Burles to the other, less front-and-center characters, and to details of the recording space.

Newton Road
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(450) 449-2212

xsipower's picture

Well after years of being on the sidelines I decided to voice my concerns for the high end industry. Since my teenaged years I have loved the listening to good music through good equipment. I became an Electrical and Mechanical engineer, which was due in part to my love for building my own DIY equipment at home.

After reading Stereophile’s review of the Simaudio’s Moon Evolution 800M, I just couldn’t stand on the sidelines and not voice a concern about specmanship in the highend audio industry. I thought the large differences in published specifications vs. actual measurements was relegated to consumer electronics and not to five and even six figure (hopefully) state of the art audio equipment. The Evolution 880 clearly does not achieve some of the most important specifications that amplifiers are measured to.

Here below I distilled my concerns and finding:

Spec’d Output Power 8 ohms: 800W in 8ohms   

Measured Output Power 8 ohms: 800W in 8 ohms

Meet Spec.: Yes


Spec’d Output Power 4 ohms: 1600W in 4 ohms

Measured Output Power 8 ohms: 1050W in 4 ohms (fuse blown)*

Meets Spec.: No (<1.5x discrepancy)


Spec’d Output Current: 42A continuous

Calculated Output Current: Fuse blew into 4 ohms @ 1050W which is 16Arms

Meets Spec.: No (<2.6 discrepancy)


Spec’d Output Impedance: 0.004 Ohms

Measured Output Impedance: 0.125 – 0.132

Meets Spec.: No (<30X discrepancy)


Spec’d Frequency Response: 10 – 200Khz (0, -3db)

Measured Frequency Response:  90khz -3db

Meets Spec.: No (<2X discrepancy)


Spec’d Slew Rate: 70V/us

Actual Calculated Slew Rate: 20.5V/s

Meets Spec.: No (<3.4X discrepancy)


*With a 10A “long fast blow” fuse maximum input power is 1200W max.



The output power specification for this amplifier is continuous for only an 8 ohm load. The 4 ohm specification of 1600W is clearly momentary, or “peak” as the 10A fuse limits the output power to 1050W.

The argument that using a continuous sine wave to test amplifiers is not fair to the amplifier is incorrect. Wattage is Wattage, whether it’s from a music source or a function generator. A music source is said to have dynamics and therefore not tax the amplifier as a continuous sine wave does. This is true, but to do away with the ambiguity of testing amplifiers, the Industry uses the term as “rated continuous output power”.  If an amplifier is rated to output 800W most manufactures that follow IEC specification would specify it for continuous output power. This should be done with a sine wave a 1khz, but even if it’s done with a music source, the average power must equal a continuous 800W. Of course to output 800W of continuous RMS music power would require clipping the signal or having the music highly compressed. Power is Power. Can the Evolution output 1600W of continuous music power into 4 ohms? No.


The other very alarming measurement of the Evolution 800M is that a 1/3 power into 8 ohms the heat sinks reach dangerous temperatures. Other that than the high end amplifier industry, most manufactures limited exposed surface temperatures to 50C or less.  The high end industry seems to be fine with much higher temperatures. The Evolution 800M has surface temperatures of 73.5C. The SAFETY standard UL/ IEC 60950-1 for electronics allows for metal surfaces to reach 70C.

As with all of Simaudio's amplifier, the heat sinks are mounted with the fins in a horizontal plane rather than the traditional vertical plane. I assume they chose this for looks rather than cooling efficiency, since this arrangement is a very poor utilization of natural convection cooling. The purpose of using a heat sink with vertically mounted fins is to take advantage of the rising natural convection air moving over as large of a surface area as possible, with little or no obstruction in its motion.


I wish Stereophile would include in their review language that clearly states that the product does not meet its specification in the final summary of the measurements section of the articles. Instead in this article a poor excuse is given for it not being able to drive low impedance loads, but the review said that’s OK because music is not a sign wave. For heaven sake, this is a $42,000 amplifier and should perform as specified as do many "afordable" Best Buy purchased equipment.

I am very happy that Sterophile does actually test the equipment they listen to. Most other reviewers do not. It is a great service to all of us. The whole purpose of the review is to provide both objective and subject information to the reader so that they may know what they will be getting when they purchase the item.

I understand that the subjective portion of the review can have no objective scales, but when objective measurements are made they are very much tied to real physical scales set forth by various international agencies. My only other concern is that I have found in the last few sentences of the measurement section, a subjective assessment made of the objective measurements that not only seems to trouble others ( as I have read in posts on but myself as well. There have been recent reviews of amplifiers that for their astronomical price have very poor measurements.  At the end of the review a subject remark is made like “This is an amplifier that is as well-engineered as it is beautiful to look at.” That may be the reviewer’s opinion, but as an Electrical Engineer of 20 years’ experience and who closely follows both DIY and professional audio design, I had a very different opinion and hold the standards for saying “This is an amplifier that is as well-engineered “for such high priced equipment to a higher level. I would never have said what the review said for that product.

I am trying to be constructive with my comments and mean no disrespect to any of the reviewers.

John Atkinson's picture

To address a couple of the points you make:

1) My measurements of output impedance include the series resistance of 6 feet of approximately 14-gauge speaker cable.

2) Yes, the fuse blew under sustained drive into 4 ohms. But it is entirely possible that with a pulsed signal with a low duty cycle, the fuse would remain intact up to the clipping point. Note, BTW, that I don't hold the wall voltage constant for these tests, feeling that this is more representative of actual use.

John Atkinson

Editor, Stereophile

Robby's picture

1) 14 AWG cable has a resistance of 2.52 mOhm/foot

6 x 2.52 = 15.12 mOhms or 0.0152 Ohms which still makes the output impedance figure look bad compared to the spec.

2) Most energy will come from low-frequency musical elements and those are everything but low duty pulses. Most of them will be closer to sine waves and they will suck a lot of power when driven into speaker loads so there is still a risk to blow the fuse on bass-heavy music played loud.

JohnnyR's picture

Please be consistant at removing posts or don't bother removing any. Thanks

Just because some people can't face facts doesn't mean they are correct.

Robby is correct about the output impedance and the wire used to measure it, he is also correct that low frequency content tends to be sine wave not impulses.

This amp FAILS at a number of tests and should have been criticsed for doing so NOT praised.

We now return you to the usual excuses thanks for your patience.

John Atkinson's picture
JohnnyR wrote:
Please be consistent at removing posts or don't bother removing any. Thanks

You have been warned multiple times, Johnny R, that posts of yours that in our opinion are nothing more than abuse or trolls will be deleted without notice. You don't want your posts deleted, please refrain from personal attacks and stick to addressing the points being made by others.

JohnnyR wrote:
This amp FAILS at a number of tests and should have been criticised for doing so NOT praised.

Please think about where you learned about this amplifier's apparent shortfalls in its measured performance.

John Atkinson
Editor, Stereophile

anjeza1987's picture

I agree with your comments xsipower.Additionaly,the high temperatures,will shorten the life of the equipment.And this one is very beautiful.

And greatly appreciated the measurments carried out from Mr Atkinson.

Regards from Greece.

GeorgeHolland's picture

just change the specs to be a bit below where actual problems arose then jack up the price even more and they would have a "winner"  wink I understand it could double as heater during the cold months. This brings about the possibility of owning another amp that doesn't get hot for the summer months. A win-win for the high end dealers that wish to double their

freddiek40's picture

Hmmmm.  800 watts, 1 year warranty = $42,000


Or you could buy 2 sets of Bryston 28B.  1000 watts, 20 year warranty, $36,000 (remember this is for 4 of the 28Bs).


I think the Sims are clear losers.

John Atkinson's picture

freddiek40 wrote:
Hmmmm.  800 watts, 1 year warranty = $42,000

From the company's website: "The Standard Warranty is 1 year parts and labour.

"Upon receipt of a validated Product Registration (via our website or by regular mail), the warranty can be extended up to an additional 9 years.

"To receive this free-of-charge extended warranty (up to 10 years), the product must have been purchased new, from a MOON Authorized Dealer. and registered with us within 30 days of your invoice date."

John Atkinson

Editor, Stereophile

MVBC's picture

And that includes the cooling fins...

xsipower's picture

Hello Freddiek40,

If you read Stereophile's review of the Bryston 28B-SSTyou will find that it was another very “hot” amplifier.

From Stereophile review:

“I preconditioned the Bryston 28B-SST by running it at 330W into 8 ohms for an hour. ….. The amplifier's heatsinks were way too hot to touch after 60 minutes, but despite the thermal abuse, the amplifier didn't turn itself off.”

What is way too hot to touch? This can be quite subjective, but is usually considered starting between 65-70C. That is when contact for more than a brief few seconds leads to a burn. The Bryston 28B-SST temperature was clearly above this threshold based on Stereophile’s test.

I would not consider the Bryston 28B-SST to be designed thermally any better than the Evolution 800M. That being said, the Bryston 28B-SST functioned through the entire tests without failure.

I agree that with higher temperature two things must be considered by a buyer. First is the placement of the equipment where it will get enough ventilation as well as not being touched when driven hard.  The second consideration is that the MTBF (Mean Time before Failure) increases with higher operating temperature. Temperatures of 70C are not destructive to most electronic components since most are rated much higher. The component that is most affected by high temperatures are electrolytic capacitors the bulk of which are the main power supply filter/storage capacitors. The life time of these are impacted quite drastically as temperatures go up.

 You would defiantly want a robust warranty on a “hot” running amplifier.

I appreciate the difficulty that designers of amplifiers face. There are many unknowns to the designer. The most unknown is the load. Some speakers are easy to drive, some are very difficult. Speakers are complex loads and can drop their impedance to half or less of their rated impedance at certain frequencies. Not only that, but during these low excursions the current and voltage can be way out of phase and that puts the highest stress on the amplifier’s output transistors.

 I believe that over the many decades that this industry has been around; the adoption of standardized testing methods and specifications has helped to alleviate the ambiguity of how a particular amplifier can perform.  Tests like the 1/3 power test into load, the specification of continuous RMS power into 8,4 or 2 ohms loads, etc., give the buyer the tools with which to marry a speaker with an amplifier. Of course the tests do not reflect “real life” music listening, but they are not meant to. They are meant to give assurance that they can at least play music continuously at a rated power in to a rated load.

Do we listen to music at continuous RMS value of let say 800W. Most likely not. But then, what music are you listening to. Is it highly compressed? Does it have a lot of low frequency component which where most of energy goes in recreating music. What speaker are you driving?

ON…and On….

John Atkinson's picture

xsipower wrote:
What is way too hot to touch? This can be quite subjective, but is usually considered starting between 65-70C. That is when contact for more than a brief few seconds leads to a burn. The Bryston 28B-SST temperature was clearly above this threshold based on Stereophile’s test.

The Bryston was reviewed before I bought an infra-red thermometer. But I was taught at university that "too hot to touch" or more accurately, to keep your hand on" was equivalent to >60C.

And the one hour at 1/3 power test is very much a worst case for amplifiers with a class-B or -AB output stage like the Bryston and Simaudio.

John Atkinson

Editor, Stereophile

xsipower's picture

Thank you Mr. Atkinson for the elaboration on "too hot to touch". Yes I agree that 1/3 power is very rigorous on the amplfier with a class-B or AB output.

xsipower's picture

Sorry. I need to make a correction in my above post. I wrote "MTBF increase with temperature". That I wanted to write was MTBF decrease with increase in temperature.

tmsorosk's picture

Yeah the Brystons are clear winners until you hear both offerings , then there is one clear winner ( Simaudio ). Warranty and watts are one thing but for the true audiophile your ears must decide .

JohnnyR's picture

Sorry but , "I think this amp sounds better" with no objective testing is guess work and just opinion. Amps need to meet their specs otherwise the manufacturer is making a faulty product. If they can't meet their own specs then how can you trust it to last or perform at it's best?

GeorgeHolland's picture

My oh my with such an under engineered amp, they are going to see plenty of repairs that is if anyone buys it to begin with.