CH Precision M1.1 power amplifier

CH Precision's massive, versatile, technologically sophisticated, 165 lb M1.1 power amplifier ($54,000 configured for stereo) can easily crush your foot if you're not careful when installing it. But the more important consideration is this: Can this cool gray techno-square sing and dance without stepping on its own feet?

Unlike their playfully mischievous neighbor darTZeel, whose corporate sense of humor runs so deep that the LCD readout on their NHB-18NS preamp displays the messages foreplay and climaxed when working its on/off switch, Swiss manufacturer CH Precision is all business. Founded by Florian Cossy and Thierry Heeb (hence the company name—although, coincidentally, CH also stands for Confoederatio Helvetica, the Latin abbreviation for Swiss Confederation), CH Precision is a relatively young company, though the founders have a long history in high-performance audio beginning in the 1990s with their work for Goldmund. The two left that company to form OEM Anagram Technologies, which quickly established a fine reputation for its DACs, among other products. In 2009, with the encouragement of a group of distributors, the partners founded CH Precision.

Modular design
Like all CH Precision products, the M1.1 is an unusually flexible design—so much so that, although you wouldn't know it from the headline, I reviewed two of them, as monoblocks. Each M1.1 contains two power amplifiers and can be configured in any of five different modes. The simplest of these—and the only one that requires just a single M1.1—is stereo mode, in which the M1.1 outputs 350Wpc into 4 ohms. But because each M1.1 is shipped with only a single input card, stereo mode requires the purchase of a second card ($2000).

After that, there are four different ways of using a pair of M1.1s:

• Monaural mode, which uses only one output section per amp, yet which diverts to that board the entire output of the amp's massive power transformer. In this mode, the M1.1 can deliver up to 350W into 4 ohms.

• Bridged mode, in which both output sections per chassis operate together as a single balanced amplifier, outputting up to 1200W into 4 ohms.

• Passive bi-amplification mode, in which the two output sections per chassis separately drive the two pairs of input terminals on a bi-amplifiable speaker. Interestingly, in this mode, feedback and gain can be independently adjusted for each pair of terminals, to more precisely match the individual speaker segment's efficiency and sonic characteristics.

• Active bi-amplification mode, which also requires the purchase of an additional input board—for each amp—and allows the use of an external crossover. As in passive bi-amplification mode, feedback and gain can be independently adjusted for each pair of speaker terminals.

The modular design allows end users to order an M1.1 with a single analog input board for both monaural and passive bi-amplification use, and later add a second analog input board for active bi-amplification mode or, if times get tough, sell one amp and add the second input card to create a stereo amplifier. Speaking of tough times, a pair of M1.1s configured as monoblocks (with a single input board each) costs $104,000.


The M1.1 was created in June of 2018, as an upgrade from their M1 power amp. For the new model, the single 100,000µF power capacitor of the original was replace by a pair of "monstrous" (according to the CH website) 120,000µF ultralow-ESR/ESL capacitors, for a total storage capacity of 240,000µF per chassis. This upgrade brought about a $3000 price increase from the old model to the new; for the same $3000, CH will ship the upgraded parts to the customer's home and, for no additional charge, send a technician to perform the install. The manner in which a company handles their "legacy" customers tells you a great deal.

The power supply, occupying most of the chassis interior, features a massive 2200VA transformer that's magnetically and electrostatically shielded and mounted on vibration-reducing blocks. The analog stages feature discrete components only and the shortest possible signal paths. No capacitors are in the signal path, nor does the circuit use output relays.

The JFET-based, fully differential input stage runs in class-A, while each output stage, featuring six pairs of complementary output devices, is biased for class-AB. CH Precision uses OnSemiconductor's ThermalTrak devices, which make possible the precise monitoring of the operating temperature of each transistor's circuit or silicon die, in order to keep output-stage bias as constant as possible—independent of ambient temperature or the demands placed on the circuit by varying music signals. CH claims that the M1.1's class-AB design, using their patent-pending circuitry, outperforms a typical class-A biased amplifier. Claimed frequency response is wideband: DC–450kHz (–3dB) at 1W—which in the words of the old British comedy duo Flanders and Swan, in their "Song of Reproduction," "should please any passing bat!"

A DSP-based protection system, operating at a sampling rate of approximately 100kHz, monitors output voltage and current. An abnormal condition immediately shuts down the amplifier to protect the loudspeakers in the event of a short circuit, or a disconnected speaker, or an over-temperature heatsink or over-temperature output transistors—all accomplished without relays.

Built using pin assembly, the M1.1's chassis of high-grade aluminum alloy conceals the front-, top-, and side-panel fastening screws, producing smooth joints between metal parts, while the solid steel baseplate provides a firm mechanical foundation and effective magnetic shielding. Despite its high mass, the M1.1 can, if necessary, be spiked and vertically stacked using an ingenious engineered-in system similar to that in other CH products.

Though at first glance the M1.1's industrial design appears square and austere, a closer examination reveals a satiny finish that's luxurious to the touch and visually quite pleasing, in an understated way. Again, the look is quite the opposite of the fanciful industrial design of my even-more-costly reference amps, the darTZeel NHB-458 monoblock (170,000 Swiss francs/pair).

Complex yet user-friendly setup
Each M1.1 requires two AC cords: A 20A IEC jack supplies power to the aforementioned 2200VA toroidal transformer, while a 15A jack connects to a second toroidal transformer, which powers the small-signal stages as well as the amp's digital functions (front panel display, microcontroller, and DSP features). (A third toroidal transformer that draws only 1W insures "green" operation when the amp is in standby mode.)

Once the amps are in place—hopefully accomplished without injury—an ingenious footer/spike system is used to level the chassis and help draw away mechanical vibrations. The M1.1's rear panel includes the above-mentioned two AC sockets plus two pairs of Argento Audio speaker terminals. The input board features two single-ended jacks—one RCA, one BNC—and an XLR socket for balanced input, as well as an XLR balanced "pass through" output in case the user wishes to "daisy chain" multiple M1.1s. The rear panel also includes separate grounding jacks for analog and digital circuitry—two for the former, one for the latter, all banana sockets—in addition to a USB port for software updates and an Ethernet port to facilitate network operating system control via the CH app.

CH Precision
ZI Le Trési 6D
1028 Préverenges
(41) (0)21-701-9040

jeffhenning's picture

Another amp that costs more than a sports car that does not offer anything close to state of the art performance.


Michael Fremer's picture

Of "state of the art"? Mine is: "a seriously mis-used and meaningless cliché used by lazy people."

jeffhenning's picture

So I'm getting flamed by a guy who thinks you need to spend $5K on each power chord to have a good sounding system.

Given your history of thoroughly misguided and erroneous "journalism" (which, in your case, the term is used very generously), having you slag me is a sign that I'm not wrong.

What I consider "state of the art":

• Amps that produce at least 20dB less distortion and noise than this overpriced brick

• That list, to my knowledge, has only two entries: amps by Benchmark and Devialet

• I'm confident that whatever Bruno Putzeys & Peter Lyngdorf are about to release from Purifi Audio will be way better than this cinderblock as well

• Also, all of these superior products are a fraction of the cost of this lead bar

Fremer, you are definitely that guy that would buy a Bugatti Veyron rather than an Acura NSX or purchase a $10K analog Rolex when a $400 Citizen, solar powered, digital watch keeps better time.

Perfect_sense_audio's picture

Based on what criteria exactly? Did you experience these amplifiers at all?

Ortofan's picture

... sound quality of this amp when powered through a "Best Buy grade" Audioquest power conditioner. Surely anyone who reads - let alone writes for Stereophile - knows that he should have been using a power conditioner from Synergistic Research.

Now bring on the 350W/ch Rotel RB-1590:
It's much lighter on both your wallet and your toes.

Bogolu Haranath's picture

Rotel RB-1590 doesn't have user adjustable feed-back controls :-) .........

Bogolu Haranath's picture

MF liked the way D'Agostino Momentum mono-blocks sounded ....... Momentum has similar output impedance as CH precision, when 20% feed-back is used ........ That output impedance is also close to the output impedance of darTZeel NHB-458 amp :-) ..........

Bogolu Haranath's picture

CH precision is smart ....... They know that 'one size fits all' approach may not be a good idea ....... So, they provide user adjustable feed-back controls :-) ........

Bogolu Haranath's picture

BTW ..... Pass labs SIT-3 ($4,000) also has somewhat similar 0.25 to 0.26 Ohm output impedance :-) ........

Archimago's picture

Yeah, I think CH has hit on an interesting feature that audiophile might like. Sort of like letting listeners choose between a range of digital filters from minimum phase to linear. Although this of course will result in more audible differences than otherwise decent digital filters at the edge of audibility.

The problem here I hope is that it does not demonize negative feedback as something "bad" (which IMO it isn't). If some people are OK with the higher harmonic distortion including elevated higher order distortions and higher output impedance (with commensurate lower dampening factor), then so be it.

But let's just make sure to frame this as a "subjective choice" rather than making it some kind of simplistic audiophile "myth" causing all kinds of companies to follow a trend of low negative feedback when there's typically no reason to...

ok's picture's not theory but implementation that matters.

Bogolu Haranath's picture

Agreed :-) ........

Bogolu Haranath's picture

Wish more audiophile companies could do what CH Precision is doing less expensively :-) ........

Glotz's picture

that this amp is State of the Art in many areas of performance.

Many reviews from respected magazines with experienced reviewers can attest.

Instead the posts show misanthropic assumptions of equipment none of us have heard.

Ortofan's picture

... exceed the performance of the $4K Benchmark AHB-2 (operating in bridged mode)?

Glotz's picture

and listen... Only then would you know where and how the amp compares.

The review should be insightful regarding sound quality.

Perhaps you could ask MF to compare them in a follow-up.

Or you could read the several, other reviews on the web and guess.

Or you could do none of the above, and just speculate wildly and assume everyone is lying to you.

Ortofan's picture

... the CH Precision M1.1 is "State of the Art in many areas of performance."
Again, which MANY areas of performance would those be as compared to the Benchmark AHB2?
For your reference:

Glotz's picture

My statement was a rebuttal of your assertion.

Read the reviews and you tell me... I already read them. lol..

Michael Fremer's picture

Really think measurements tell you how things sound? On the basis you'd not be listening to vinyl.

Ortofan's picture

... sound storage and playback via analog disc, then you must have a preference for a less flat frequency response, degraded speed accuracy and pitch stability, higher levels of distortion and worse signal-to-noise ratio, along with the presence of random impulse noises, as compared to a digital system.

JRT's picture

In a large active system, bridgeable Benchmark AHB-2 can provide clean linear output with wide bandwidth, fully adequate for powering the tweeters. If DIY is of interest, consider the Neurochrome Modulus-686.

Below tweeter frequencies... Bandwidth is obviously constrained at lower frequencies, and class D is fully adequate, and the inefficiency of class A/B is not justified. In that range, look at ATI 5xxNC family of amplifiers which use Hypex NC500 amplifier modules.

For the subwoofer subsystem, I would suggest class H pro-grade fan cooled amplifiers, and would suggest replacing the cooling fans with suitable very quiet running Noctua fans. Class H is similar to class A/B in the output stage, with tight control provided by a large dose of negative feedback, but modulates switch mode power supply output rail voltage to follow the input signal, keeping it a little above a level that would otherwise clip the output when operating within design range. So it is much more efficient than class A/B. The downside is that bandwidth is lower than is achievable with conventional class A/B.

Horses for courses, etc.

David Harper's picture

I guess some people just have too much money.Considering the state of the world today anyone who buys this amp will have some explaining to do when he goes to meet his maker.

ACranston's picture

I'm sure there are a lot of dirt poor people in 3rd world countries who could look at your possessions and your lifestyle and say the same about you. Take your "holier than thou" attitude elsewhere.

David Harper's picture


Glotz's picture

He's worried about God judging him? For spending money on the stuff that gives him joy and happiness? Right.

misterc59's picture

Well said ACranston


Michael Fremer's picture

That is among the most foolish comments yet. No one need apologize for owning this amp, or any high performance, high quality product. Should Ferrari owners apologize? Where do you draw the line? Grow up.

Bogolu Haranath's picture

MF did not quite like the sound of Boulder 2150 mono-block power amps (Stereophile Class-A) ....... 2150 has very low output impedance and very high damping factor ....... 2150 also has almost 20-Bit resolution (SNR) :-) .........

Ortofan's picture

... why not get a Nagra?

Bogolu Haranath's picture

That would be a 'bravura' effect :-) .........

Bogolu Haranath's picture

Both CH Precision and Nagra are located in the Swiss 'Watch Valley' :-) ..........

Bogolu Haranath's picture

darTZeel is also, Swiss made :-) ........

Next MF is gonna review the latest darTZeel NHB-468 monoblock amps :-) .......

blang11's picture

The comments section beneath many Stereophile articles are consistently hijacked by a vocal minority of judgmental, know-it alls that simply can't summon the capacity to stifle their negative rantings. I, for one, vote to turn off comments. Another one of my favorite audio review sites did it, and the world just kept on spinning. I would be surprised if Stereophile hasn't considered doing this already. I'd be interested to hear your thoughts in an "As We See It" one of these days.

ok's picture

..simply refuses to get into the comment section; I guess they call it a smartphone for a reason.

John Atkinson's picture
ok wrote:
My android phone simply refuses to get into the comment section; I guess they call it a smartphone for a reason.

The mobile version of the Stereophile website doesn't show comments.

John Atkinson
Technical Editor, Stereophile

Bogolu Haranath's picture

Idee intelligente :-) .........

JRT's picture

First, thank you for providing the comments section.

In writing this comment, I am using a Chrome browser on Android, and the comment section becomes available by selecting the desktop site in the pull-down menu in Chrome. As you explained, the comment section is unavailable in the mobile version.

I would suggest that if anyone does not want to read the comments, then perhaps they shouldn't. They always have the option of not reading the comments, regardless which browser they might be using.

JRT's picture

I like reading the comments, and sometimes adding my own comments.

Ortofan's picture

... a pair of CH Precision M1.1 amps OR a pair of Luxman B-1000f amps - plus a BMW Z4.

Bogolu Haranath's picture

....... or, a Corvette convertible :-) .........

Bogolu Haranath's picture

Invasion of the 'know-it-alls' :-) ............

Bogolu Haranath's picture

May be Stereophile could come up with an 'app' for the comments section ....... So, people who don't want to read the comments, could turn off the 'app' :-) ...........