I’m a sucker for the double-down solid-state power amp. But to explain what this means and why it’s important to me I need to start about 30 years ago.

While I’ve always been passionate about home audio, I used to be rabid about car audio, and three decades ago I became very good friends with Colin Kay, owner of Autoworks Car Audio, here in Toronto. Colin introduced me to such esoteric concepts as tube monoblock amplifiers and external DACs (this was about the time Audio Alchemy pioneered the affordable DAC). He also infected me with Mobile Bass Disease.

While really high-quality home-audio bass, and the standalone subwoofers that make it possible, is a fairly expensive endeavor fraught with missteps and the potential for abysmal sound, in car audio it’s quite simple: Throw two or three high-end drivers in a fairly small, well-braced box (0.75 cubic feet per driver is fine), power them with a big, nasty solid-state amp, and you’re good to go. JL Audio was my car-sub maker of choice even back then, and I was in love with Soundstream’s car amps. Soundstream’s Reference Class A 6.0 was claimed to put out 25Wpc into 4 ohms, but it would double that power each time you halved the impedance: 50Wpc into 2 ohms, 100Wpc into 1 ohm -- or bridge it to mono and the Class A 6.0 would double its output again. Bottom line: into 0.5 ohm in bridged mono, the little A 6.0 churned out 600W. So line up a bunch of subs in parallel and you’ve got a whole whack of Mobile Bass.

How does this translate into home audio? It doesn’t, really. We have no need to parallel a string of subs and run them off one amp, because we don’t have space constraints -- in home audio, more boxes is more cool.

But through the years, the concept of doubling down stuck with me. While it gave me a frisson of pleasure that was equal parts pride of ownership and nerdy fascination, and was the bedrock my car-audio feet stood on, nowadays knowing that an amp is capable of doubling its power when the impedance is halved still reassures me, even though there’s no real technical or sonic need for it. It just makes me smile.

Simaudio Moon Evolution 860A

Which was why I smiled at Simaudio’s Moon Evolution 860A amplifier ($15,000 USD), even as I almost dropped a nut trying to manhandle this dense, awkwardly shaped box into my listening room.


The Moon Evolution 860A is specified as producing 200Wpc into 8 ohms, and sure enough, it doubles its rated power output as the impedance is halved, generating 400Wpc into 4 ohms. Simaudio doesn’t quote power ratings for lower impedances, instead stating that the 860A produces “Output stable to any known speaker impedance.” That didn’t quite satisfy my inner doubling-down nerd, so I asked for clarification.

According to Costa Koulisakis, VP of Simaudio’s Customer Experience department, the 860A’s output section has a 3kW capacity per channel. Theoretically, it can double down again into 2 ohms, and squeeze out even more watts into 1 ohm. However, the amp’s physical size and its production of heat to some degree limit its real-world power output into extremely low impedances.

In a home audio system, the 860A would have few, if any, opportunities to actually confront a speaker load as extreme as those I’ve discussed earlier. So it really is enough for Simaudio to say that the 860A produces “Output stable to any known speaker impedance.”

The chunky 860A is the second model from the bottom of Simaudio’s Moon Evolution line. Above it is the 870A, followed by the 880M monoblock; and looming ominously over all of them is the beastly new 888 monoblock. But, unboxing and setting it up, you wouldn’t know that the 860A is quite far down the Moon Evolution line. At 18.8”W x 7.4”H x 17.5”D and a shipping weight of 90 pounds, it’s one heavy, unwieldy son of a bitch. Its substantial double carton probably accounts for 15 pounds of that weight, and the decanted 860A is just about manageable by one person -- but if the house was on fire, I don’t think I could save it.

Simaudio Moon Evolution 860A

The 860A’s case and chassis are entirely made of CNC’d aluminum, which no doubt is responsible for much of the amp’s mass. Further increasing its density are two separate power transformers, one for each channel: the 860A is dual-mono from the power cord in -- and out.

“Never trust a solid-state amp that runs cold,” my father used to say. Actually, he didn’t say that. The aphorism of his that stuck with me was “Carburetor is French for leave it alone.” But in my head, I hear the adage about amps spoken in his voice.

System and setup

The Moon Evolution 860A ran very cool. Given that its warp coils are armed with bipolar transistors running in class-A up through the first 5W, I would have expected it to run at least somewhat warm. But in retrospect, the huge mass of heatsink that is the entire 860A chassis likely dissipates heat far more quickly than it’s generated.

There were no tricks involved in operating the 860A. Its inputs are balanced XLR and single-ended RCA. Outputs are one set of speaker binding posts per channel. There’s an IEC power inlet. An RS-232 input and a set of 12V in and out triggers are present for use with other Simaudio products, and for integrated control of an entire audio system.

Simaudio Moon Evolution 860A

I powered the 860A with a Nordost Quantum QBase QB8 Mk.II power conditioner via a Nordost Vishnu power cord. From ice-cold, it took about 15 minutes for the 860A to rub the sleepy dust out of its eyes. For that first 15 minutes, it sounded a little closed in and muffled. But after one LP side, it opened right up.

The 860A was cautious, which I mean in the best possible way: Any sort of static snap, cable tomfoolery, or line fault triggered its protection circuit, which shut it down. This happened only three times during the listening period, and each was because of something I’d done -- such as unplug an interconnect without powering down the amp. Each time, the 860A quietly removed itself from potential harm by crossing its arms and refusing to answer my questions, its power indicator blinking stoically. All it took to recall it to duty was a press of the power button on the front panel.

Other than those three faults, all of my own making, operating the 860A was a non-event. It sat there quietly and worked. And as it generated no heat, I rationalized that it was environmentally kosher to leave it powered up at all times.


I’m a tube guy down to the tips of my toes, but that bias (sorry) didn’t stop me from having my world turned upside down by Anthem’s Statement M1 mono amps a few years back, when I borrowed them to better evaluate a power-hungry speaker that was giving my Audio Research VT100 tube amp grief. The Anthem M1s stunned me with their sound: rich, involving, utterly smooth, they had all the best attributes of tubes while exerting a dictatorial grip on every speaker I tried them with.

Since then I’ve often looked askance at my ARC VT100 (which is getting long in the tooth), and wondered why I don’t just move it on down the road and replace it with a decent solid-state amp. The Anthems showed me that solid-state really is getting better these days.

Then along came the Simaudio Moon Evolution 860A. Nervous, I gingerly inserted it in my system. Would this big, heavy, Canadian amp replicate my prior experience with those slim, fairly light, other Canadian amps?

Why, yes. Yes, it would.

Simaudio Moon Evolution 860A

Two or three albums in, my shoulders dropped. I slouched down into my couch with an audible sigh of relaxation. Expectation bias? Hardly. I’d anticipated a neutral, crisp sound, a python-tight grip on the bass, and superb resolution of detail. In short, I thought I’d hear all of those clichés about the sound of big, expensive solid-state amps.

Instead, I heard something I’ve always desired but, before the Anthem M1s, had always thought unobtainable: jet-“black” backgrounds and infinite resolution of detail and smooth, sweet, delicate highs.

If you’ve read any of my past reviews, you may have noted that I tend to harp on about how, for me, musicality trumps detail. I would far prefer to listen to a euphonic, rolled-off-sounding system with mushy bass and a recessed upper midrange than suffer through a crisp, bright, hi-fi presentation. I don’t want to hear a stereo system.

But really, that’s me taking it to an extreme -- I’m always happy listening to the middle ground. But there’s no room in my listening room for tipped-up treble masquerading as detail, and any form of glare in the midrange will draw my ire.

Back to the Moon Evolution 860A. This amp was the middle ground, the baby bear’s bed that was just right. With my first listen to any new component, I’ve noticed that I unconsciously reach for an album that will flatter my system. This time it was an out-of-the-park home-run vinyl reissue of Miles Davis’s A Tribute to Jack Johnson (LP, Columbia/Legacy/Mobile Fidelity Sound Lab MFSL1-440). While the CD version of this album is damn good, the MoFi biscuit is utterly magnificent. This is crisp, dynamic, rockin’ music -- jazz possessed by Led Zeppelin. With Miles Davis. On acid. Just because the 860A is so bloody heavy, I first focused on the low end -- Michael Henderson’s bass and Billy Cobham’s kick drum had noticeably more physical presence, along with a roundness and body that my ARC VT100 could never hope to match.

Bass that was full and weighty, chock-full of richness and chocolate, all bundled up with just the right amount of control -- that’s what I got in my first five minutes with the Moon Evolution 860A.

Audiophiles, stop reading right now -- I’m going to listen to Tom Waits, and you know how you get when some [ahem] roughneck plays him at an audio show.

Simaudio Moon Evolution 860A

Still there? Good. Waits’s Real Gone (LP, Anti- 86678) is just full of difficult, angular music and it’s been an essential weapon in my reviewing arsenal since its release in 2004. Listening to “Shake It” via the 860A was instructive. That’s Les Claypool of Primus on bass, which is odd, but then Waits runs with a rough crowd. The sound is loose and sloppy, and Claypool’s bass has to fight for air against Marc Ribot’s slurred buzz-saw guitar. What was really nifty was how I could switch my aural focus between the bass and the guitar -- kind of like closing one eye, then the other -- and hear my focus point shift position.

This exercise showed me two things. First, “Shake it” -- heck, the whole album -- is abrasive as hell, and if the 860A’s sound were bright or etched in any way, it would have driven me out of the room. But after I’d sat there listening for a moment, I walked over to my preamp and throttled it up a couple notches. Now it was Loud. My Focus Audio FP60 BE speakers are fairly large stand-mounted monitors, and they’ve taken some serious abuse from me in the last few years, so I wasn’t worried about smoking them. Yeah, it was Loud, but with no sense of strain from speakers or amp. Another couple rungs up the volume ladder and the woofers looked as if they were being beaten with a stick. Still no strain -- and still I could clearly delineate guitar from bass, in a way that either a) I’d never really tried to do, or b) I’d never been able to do. I’m betting on b) -- the 860A felt to me as if it was overtly controlling the musical signal in a most complimentary way.

More complicated, more dense music: Charles Mingus’s Mingus Mingus Mingus Mingus Mingus (LP, Impulse! IMP-170) has a whole lot of thrashing going on. Through a shitty system, “Better Get Hit In Yo’ Soul” degenerates into amusical noise, but when the planets align, it’s spiritual. My arms were raised and my head was back listening -- yes, again -- really Loud. I’ve often found that Mingus’s double bass fades into a general mush of instruments with this album, but not via the Moon Evolution 860A. Without straining, I could easily distinguish every one of the 11 instruments played.

I’ve spent a while just talking about bass instruments, and I hope I’m not giving the impression that the 860A was heavy-handed down low. Far from it. Letting Mingus Mingus Mingus Mingus Mingus play on: “Theme for Lester Young” (which is essentially “Goodbye Pork Pie Hat”) showed just how incredibly musical this honkin’ great amplifier could be, just how delicate it could be when it felt the need: the slowly pulsing reeds in this track, the gentle counterpoint of the piano, rendered just so by an integrated circuit. Before hearing this track played by this amp, I’d have been certain that it would take tubes to satisfy me to this extent.

Why so effusive, Jason? Well, “Theme for Lester Young” is redolent with sadness -- a slinky, sinuous melody played over a plodding bass line plucked straight out of a New Orleans funeral parade. There’s so much that can go wrong in the sound -- the mix of horns and reeds can be steely, and I’ve heard them cross the line into glare. Not so with the 860A, which kept them just this side of silky while adding no molasses to the upper mids and highs.

And I don’t think I’d ever heard this track image like this. I could easily pick out each instrument, hear its position in space. I could “see” it. The Moon Evolution 860A excelled at depth, setting up vibrant images way behind the speakers. In fact, it felt as if the 860A was pushing images just a tiny bit behind the plane of the speakers, but really, it was more that there was just so much depth of image that soundstages felt as if they’d grown another room.

Simaudio Moon Evolution 860A

An extended and silky treble -- that’s my gatekeeper for musical enjoyment. All other planets can align, but the upper range must walk to heel, or else an audio system is just pissing into the wind. For a couple years now I’ve been listening to Shallow Grave, the first album of The Tallest Man on Earth, aka Kristian Matsson (45rpm LP, Gravitation gra028), and it never fails to energize me. Think a Swedish Bob Dylan, but with boundless energy. Matsson’s English is reportedly not that good, so his lyrics receive odd translations -- as in “Pistol Dreams,” in which he sings “and I will boil the curtains to extract the drugs of springtime.”

Isn’t that wonderful? The sound on this 45rpm LP does wonderful justice to the rapidly strummed guitars and nimbly picked banjo. Both instruments were rendered by the 860A with tons of air and believable harmonics. The strings floated in space between my speakers like a lacy nightdress pierced by sudden bolts of electricity. It’d be really easy to overcook the highs on this album, but the 860A did a perfect tightrope walk, keeping all the life and sparkle in the overtones while never adding the slightest hint of glare or artificial enhancement.

Despite all of my earlier ravings about the Moon Evolution 860A’s bass, to me, the Simaudio amp’s biggest selling point was how well it walked that treble line. It steadfastly refused to sound like an amplifier, and that, I say -- as I short-circuit my logic module -- is how the ideal amplifier should sound.


Looking back, I think that maybe I’ve been a bit too effusive in my praise of Simaudio’s Moon Evolution 860A. But I’ve listened to more music in the last few months than I have in maybe the last year. The last few additions to my system have been fortuitous: JE Audio’s HP10 phono stage, the Moon 860A, and now Pro-Ject’s RPM 10 Carbon turntable (review forthcoming) are working together so very well that, down here in my basement, I’m experiencing a bit of an audio renaissance.

Then again, the Moon Evolution 860A damn well should sound good. In the dollars-per-watt steeplechase, this $15,000, 200Wpc amplifier lags far behind a value-for-money brand. But there’s no doubt in my mind that in this case you get what you pay for. The Simaudio is a solid, heavy amp that in no way was built to a price point. It looks and feels like a luxury product, and does it ever sound like one. It’s a solid-state power amplifier that I could easily and happily live with for the long term. Coming from Jason the Tube Guy, that is praise indeed.

. . . Jason Thorpe

Associated Equipment

  • Analog source -- Pro-Ject RPM 10 Carbon turntable and tonearm, Roksan Shiraz cartridge, Ortofon Quintet Blue cartridge; VPI Cyclone record-cleaning machine
  • Digital source -- Logitech Squeezebox Touch
  • Phono stage -- AQVOX Phono 2 CI, JE Audio HP10
  • Preamplifier -- Sonic Frontiers SFL-2
  • Power amplifier -- Audio Research VT100
  • Speakers -- Definitive Technology Mythos ST-L, Focus Audio FP60 BE
  • Speaker cables -- Nordost Frey
  • Interconnects -- Nordost Frey
  • Power cords -- Nordost Vishnu
  • Power conditioner -- Nordost Quantum QBase QB8 Mk.II

Moon by Simaudio Evolution 860A Stereo Amplifier
Price: $15,000 USD.
Warranty: One year parts and labor; ten years with product registration.

Simaudio Ltd.
1345 Newton Road
Boucherville, Quebec J4B 5H2
Phone: (450) 449-2212

Website: www.simaudio.com