CH Precision M1.1 power amplifier Jim Austin March 2024

Jim Austin wrote about the CH Precision M1.1 in March 2024 (Vol.47 No.3):

At Stereophile, every reviewer takes a different approach to reviewing, and so they inevitably reach varied conclusions. Our work, though, is partly based on shared principles. As in reviewing wine, for example, our own tastes matter—a lot—but certain universal (though subjective) principles matter, too. This fact becomes especially interesting in follow-up reviews, in which shared principles hold even as personal preferences collide.

As long as it's done by a different reviewer, a follow-up review always adds one new thing: another reviewer's perspective. Usually there are other differences, too: a different reviewing system, for example, and a different room. With complex products—including the CH Precision M1.1 power amplifier (footnote 1), which I'm reviewing here—it may be used in a completely different way. A re-review may result in some new sonic insight—a new perspective on how the product sounds, something the original reviewer overlooked.

Sometimes there's an ulterior motive for doing a follow-up review—something other than a desire to present a different perspective. That is the case here. The CH Precision M1.1 power amplifier was first reviewed in our July 2019 issue. It is now 2024, more than four years later, and the M1.1, despite its merits and despite still being a current product, has fallen off our Recommended Components list (footnote 2).

Assuming the product didn't somehow get worse over the last four years and that the state of the art of audio amplification hasn't lately advanced very fast, the M1.1 belongs on the list. To be confident, though, a Stereophile writer must listen to it again. That onerous task fell to me (footnote 3).

Michael Fremer wrote that original review, in the context of a different system, and he used the amplifier differently. His speakers were very similar: He reviewed the M1.1 with the Wilson Alexx. Coincidentally, I am using the Alexx's successor, the Alexx V. Mikey used a dCS digital front-end and a darTZeel preamplifier. I'm using a CH Precision front-end—specifically the C1.2 D/A processor—and two preamplifiers: the CH L1 (review forthcoming) and my reference Pass Laboratories XP-32.

The rooms and setups were also different. Mikey listened relatively close, almost in the nearfield. My room is large, and I sit some 12' from the speakers. We both used balanced connections and plugged the M1.1—two of them in Mikey's case—directly into the wall.

Like other CH Precision components, the M1.1 is modular. It has five distinct operating modes, described by Mikey in the original review, four of which require two M1.1s. Mikey used two M1.1s in what CH Precision calls "monaural" mode, a configuration that at today's prices would cost $104,000. In that setup, only one output stage per amplifier is used, but that output stage has access to the vast resources of a whole M1.1 power supply, including the full output of the power transformer and 240,000μF of storage capacitance. I, on the other hand, have a single M1.1, and I'm using it in stereo.

In both configurations, the amplifier is said to be capable of 350Wpc into 4 ohms, but in Mikey's setup, the power supply is expected to be much stiffer. Whether that difference is meaningful is a key question, since even half the M1.1's power supply is formidable.

This follow-up review will not resolve that question, nor will it describe the product comprehensively; if you're interested in this amplifier, read the original review. Mikey did a good job communicating the essence and features of the M1.1. Also, I agree largely—though not completely—with his conclusions, which are well summarized in a passage from his review: "The M1.1s dug deeply into the musical action, well-paced and with confident but not excessive grip, and they moved with sufficient speed to deliver rhythm'n'pacing excitement on recordings in all musical genres." Mikey's "confident but not excessive grip" was especially insightful. It is possible for an amplifier to grip a speaker—and the music—too hard. Perhaps that's where the M1.1's feedback control comes in.

Yes, I said feedback control. You can set feedback from local-only through 100% global in 10% steps. If you're using two M1.1s to biamp a pair of speakers, you can even set each channel to use different amounts of global feedback—one value for the higher frequencies, a different value for the bass, for example.

Mikey chose 20% global feedback, observing that if he set the feedback any higher, the amplifier sounded constricted, while "less than 20% feedback pushed the sound beyond liquid, into a place that bordered on being soggy." This is my main point of disagreement with Mikey's review. That 20% figure was suggested by CH Precision's Ralph Sorrentino. Recently, Kevin Wolff, also from CH Precision, told me that most users set the feedback lower.

Before moving on to listening, I'll mention one issue that, in the context of a profound love for musical experience, may seem rather trivial, but which caused me some frustration. CH Precision components are controllable with an app; an Ethernet port on the back of each component puts it on your local network (footnote 4). The app is intuitive and comprehensive. The problem is that there is no iOS (iPad or iPhone) version; it is only available for Android. I have no objection to Android, but I'm not as familiar with Android as I am with iOS. I also found the app power-hungry: Unless I made a point of closing it after use—it is only needed for setup—the new-looking tablet I was loaned was out of juice the next time I needed it. And the tablet charged very slowly, even with a high-watt charger.

Even for setup, the app is not essential. You can make all adjustments from the front panel. But that's less convenient, and it's fun to make adjustments on the fly, especially feedback adjustments, and that is best done from the listening seat.

Speaking of listening seats
I was excited by the opportunity to play with variable feedback, but in the end I found this anticlimactic, first because changing the feedback setting had less impact on the sound than I expected it to, and second because, for me at least, the useful range was between about zero and 20%—limited, as noted, to 10% steps; beyond that, more feedback didn't seem to change the sound that much, and I didn't care for it anyway. This, surely, is why CH turned to finer steps for its 10-series amplifiers.

I settled at 10%, but I was equally happy with no negative feedback. In contrast to Mikey's experience, I did not find the bass soggy even with feedback set to zero.

Now for some things I do agree with, lifted from Mikey's review. The M1.1 has "powerful bass grip and remarkable slam." The M1.1's "impressive weight was accompanied by precise attack, generous but well-controlled sustain, and rapid decay, so the well-textured drum sound surprised me as it should have—like a depth charge—without sounding overripe, losing its grip, or hanging around too long." Ella Fitzgerald's vocals "took on a smoother, creamier tonality than I expected, combined with an enjoyably solid, three-dimensional vocal image." The M1.1 "demonstrated the sort of rich, generous midrange I associate more with tube amps than with solid state ones. Yet that richness didn't obscure the clarity of the bow strikes or the juxtaposition of the cello's solid, three-dimensional image." Brass, meanwhile, "had sufficient metal bite to sound convincing." All true.

Some original observations. On "Calling for the Dawn" from La Muralla (Glass Walls) Suite, from the wonderful 2022 album Crisálida by Danilo Pérez and the Global Messengers (16/44.1 FLAC CD rip, Mack Avenue MAC1178), I heard—I felt—a remarkable sense of openness. Well-separated instruments were laid out in an otherwise empty, blank space. This is a very dynamic, percussion-heavy track, with piano, vocals (including spoken voice), and cello. There's a lot going on, and it is all nicely sorted, nicely spread out spatially, never getting in its own way, making for a relaxing, stress-free listening experience even at high volume. This is music that can sound busy, even grating, if the system playing it back steps on its own feet (to borrow a metaphor from Mikey's review). I heard it live at Birdland just after the album's release, played by this young, tentative, highly talented band, and I love it.

Powerful, muscular, plenty of grunt, clear, open, spacious, relaxed. The soundstage (on recordings containing this information) runs from speaker to speaker, sometimes beyond, with serious depth, to the limits of what my local room acoustics can resolve. On "One Finger Snap," from Herbie Hancock's album Empyrean Isles (LP, Blue Note Classic Vinyl Series 4859562), Freddy Hubbard's solo trumpet, positioned just a hair inside the left speaker, pushed farther forward, farther in front of the speaker, than I'm used to, while Tony Williams's kit was positioned to the right, unambiguously several feet back, well behind Hancock's center-stage piano.

If you don't know it already and are looking for a sonic treat, check out Vikingur Ólafsson's album From Afar (2LP, DG 00289 486 1997). I listened on vinyl, then streaming. The program is compelling, rich in György Kurtág; what really makes it great is that it's all performed twice, once on a Steinway Model D grand and again on Ólafsson's favorite upright, one that, if memory serves, he grew up with. Both sound superb, but the experiences are totally different—see Jason Victor Serinus's take in his Recording of the Month for November 2022. On the album's first piece, an arrangement by Kurtág of Bach's Christe, du Lamm Gottes, BWV 619—and also on Theodor Kirschner's arrangement of Robert Schumann's Study in Canonic Form, Op.56 No.1 (and, really, on all the upright recordings)—the profoundly different timbres of the upright's different octaves, even between the lower and upper midrange, give the music remarkable, organlike color. And in the Allegro Moderato movement of Kurtág's arrangement of Bach's Trio Sonata No.1 in E-flat major, BWV 525, the higher notes float in space between the speakers, in front of and behind them, like little sprites, in a way that could only cause delight. In this system, powered by the M1.1, every nuance was revealed.

Highly recommended if you've got the cash. I wish I did.—Jim Austin


Footnote 1: The M1.1 costs a consequential $54,000, including the two input cards ($2000 each) needed for a stereo configuration. CH Precision Sàrl, ZI Le Trési 6B, 1028 Préverenges, Switzerland. Tel: (41) (0)21-701-9040. Web: ch-precision.com.

Footnote 2: If you're a manufacturer, and a current product from your company—one you do not plan to revise or discontinue anytime soon—has fallen off our Recommended Components list, and you'd like to have it restored, feel free to get in touch. My email address is on the magazine's Contact Page.

Footnote 3: To avoid any misunderstanding: When I write "onerous," I am being facetious. Reviewing a fine audio component is actual work—big amplifiers are heavy—but to be able to listen to such fine components cost-free, and even get paid for it, is a rare privilege.

Footnote 4: With components at this level, you probably should maintain separate networks for music streaming and control.

COMPANY INFO
CH Precision
ZI Le Trési 6D
1028 Préverenges
Switzerland
(41) (0)21-701-9040
ARTICLE CONTENTS

COMMENTS
jeffhenning's picture

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

Disappointing.

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.
https://www.stereophile.com/content/synergistic-research-powercell-ac-conditioner-mcintosh-mc462-amp-elac-adante-speakers

Now bring on the 350W/ch Rotel RB-1590:
http://www.rotel.com/product/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

..it'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:
https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier-measurements

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

nope

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

Regards,
Terry

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?
https://www.nagraaudio.com/product/nagra-hd-amp/

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.
https://www.stereophile.com/content/luxman-b-1000f-monoblock-power-amplifier
https://onahighernote.com/shop/stock-open-box-sales/electronics/luxman-b-1000f-monoblock-ex-demo/
http://www.luxman.co.jp/product/b-1000f

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' :-) ...........

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