Dan D'Agostino Momentum M400 MxV monoblock power amplifier Page 2

Sonic and musical epiphanies
I had certain expectations about what I would hear when I began my audition. I anticipated that the Momentum M400 MxV would have a similar top-to-bottom sonic signature to the Progression M550 but that its bass would be less impactful, less dynamic. Most differences, I expected, would probably be best described as refinements of that house sound Dan had mentioned. Considering that the Momentums cost some $30,000 more than the Progressions, I hoped for a great deal of refinement.

I'm always amused when my expectations are proved wrong. The strength and quality of bass with the M400 MxV blew me away. Every audiophile has their favorite recorded bass assault. One take-no-prisoners excerpt I keep referencing is the second movement of Shostakovich's Symphony No.11 as performed by the Boston Symphony Orchestra under Andris Nelsons on Shostakovich: Symphonies Nos.4 & 11 "The Year 1905" (24/96 MQA, DG/Tidal). The 400/800/1600Wpc MxV delivered bass that equaled, if not surpassed, that of the 2100/3600/6000Wpc Karan Acoustics POWERa monoblocks. I was especially drawn to the sound of the symphony's huge bass drum: Its timbre was realistic, its hollow vastness superbly realized, and the balance between leading edge, resonance, and decay of each momentous thwack was awe-inspiring.

The M400 MxV's bass superiority didn't end there. Most symphonies rest on a foundation of double basses, which, in a live concert, remains strong out to the last rows of the hall (footnote 8). An orchestra's bass section is often so strong that, if you sit the right distance from the stage, you can sometimes feel it resonate in your gut.

I'd always assumed that the Progression and POWERa monoblocks elicited as much bass from my speakers as they could possibly produce in my 16' × 20' × 9.25' listening room. Wrong again. On the Shostakovich, I was so impressed by the strength and solidity of the bass line that I felt compelled to share it. I invited my friend Scott over for a listen. Scott echoed my impression: "It's like a different recording!"

When we turned to the pounding bass in Yello's "Electrified II," from Toy (24/48 MQA, Polydor/Tidal), the first low bass thwack sounded considerably stronger than with any other amplifier that had graced my system. And every subsequent beat pounded with renewed force. On a very different work, François Xavier-Roth's Record-to-Live-For rendition of Mahler's Symphony No.4, with period-instrument orchestra Les Siècles (24/96 WAV, Harmonia Mundi HMM 905347), the reinvigorated double bass line presented in true, full sonority, rendering this piece anew, in fresh colors.

Scott asked to hear the live recording of Monk and Williams's "'Round Midnight," from Bill Evans's At Shelly's Manne-Hole (Live) (24/192 MQA, Riverside/Tidal). "Wow!" he exclaimed. Neither of us had heard such bass in this system before.

The MxV's magic, however, was not limited to its bass. "The cymbals are fantastic too," Scott said when the track concluded. "I sat on the edge of my seat."

Above its fine, true midrange, treble sounded less bright and forward on the M400 MxV than with the Progression M550. Gut-stringed baroque violins, played correctly, may have a more pointed, less rounded sound than modern violins with metal strings, but their leading edge is finely focused. The MxV faithfully conveyed that distinction. Cymbals made a huge clatter when the music called for it, but they never sounded glassy. And when Shostakovich's score demanded that horns blast and piccolos scream, they did so with convincing realism.

On Debussy's Sonata for Flute, Viola & Harp, from Debussy: Sonates & Trio (24/96 MQA, Erato/Tidal), color and contrast were striking and the intimate details of harp plucks, palpable. The depth and resonance of the Salle Colonne, in Paris, came through clearly, and sonic transparency was superb. As captivating as the sonic performance was, it was not a distraction: It was still the musical performance of this wonderful work that held me spellbound.

In my review of the Karan POWERa monoblocks, I raved about how distinctively they depicted the four period instruments on the Chiaroscuro Quartet's recording of Mozart's Prussian Quartets (24/96 WAV, BIS 7318599925585). The M400 MxV shed further light on those instruments, raising from the shadows even the subtle fricative whisper of bows as they were drawn across strings. The sound wasn't as brightly illumined as through the Karans, but it flowed with exceptional ease. The rich timbre of Claire Thirion's gut-stringed cello was particularly enchanting, and the higher- and lower-pitch instruments balanced each other ideally.

I recently reviewed the five new piano works by Vijay Iyer, Derek Bermel, Anthony Cheung, John Harbison, and Wang Lu on Shai Wosner's Variations on a Theme by FDR (24/96 WAV, New Focus Recordings FCR359; footnote 9). Wosner's piano sounded fuller and more resonant with the M400 MxV than with any other amplifier I've had at home. The piano's low end and midrange, in particular, sounded as realistic as I'd ever heard it on my system, and the vibration and decay of each note were more convincing.

Vocals were special. Soprano Sandrine Piau's recording of Carl Loewe's lieder "Ach neige, du Schmerzenreiche," from Chimère (24/96 MQA, Alpha 397/Tidal), sounded more transparent than through the Progression. I could hear the heart behind the voice. The very different, ringing voice on tenor Jonathan Tetelman's Arias (24/96 WAV, Deutsche Grammophon 4862927; footnote 10) has long been a test for my system, with squillo often obscuring all else. With the M400 MxV, I could hear the warmth at the core of Tetelman's voice on the highest, strongest, and brightest notes.

How wonderful it was to hear again, after many years, the divine voice of Kathleen Battle in "Vorrei spiegarvi, o Dio!" on Kathleen Battle Sings Mozart (16/44.1 MQA, Warner/Tidal). It's easy to understand why Battle chose to open her recital with this concert aria. Aside from a challenging high E that pushes her into the uppermost reaches of her vocal compass, this aria's tessitura lies comfortably in the middle of the most heavenly part of her range. Thanks in no small part to Christopher Parker's engineering and the Abbey Road acoustic, this recording is flawless, and the M400 MxV delivers every note as if it were a precious pearl.

D'Agostino's Momentum M400 MxV mono amplifier exceeded my expectations. Its relatively compact size belies its stellar performance: massive bass, mellifluous midrange, and well-measured treble. The clarity and ease with which it handles even the most challenging recordings is remarkable. It is one of the most musical, truthful, satisfying amplifiers I've ever heard in my system and one of the most striking aesthetically.

Audiophiles wishing to experience the edge of the hi-fi envelope should visit a dealer or an audio show exhibiting the Momentum M400 MxV and listen to it. Those who audition a pair and are blessed with the wherewithal to seriously consider their acquisition will find it tempting, I suspect, to take them home.

Footnote 8: In my experience, that depends on the hall.—Jim Austin

Footnote 9: See sfcv.org/articles/review/pianist-shai-wosner-focuses-immigrant-experience-latest-recording.

Footnote 10: See sfcv.org/articles/review/jonathan-tetelman-sings-greats.

Dan D'Agostino Master Audio Systems
5855 E Surrey Dr.
Cave Creek
AZ 85331
(480) 575-3069

jimtavegia's picture

I do like his comment about distortion as with so many liking tube amps this makes sense to me. It is also true as you review and then measure so not to be swayed by what JA1 finds out.

As hard as this is for me to say, this pair of amps at their price compared to some of the prices we read about at the recent shows that are 6 figures, this pair of amps may be a bargain for those who can afford them, as well as the fact that they look superb.

David Harper's picture

I promised myself some months ago that I wasn't going to troll this forum anymore. And, so far, I have kept this promise. 80K. 2 mono amps.
Bargain. God give me strength.

Anton's picture

Well, entry level integrated amps are now 22,000 dollars, so keeping our betters fed seems to be working!

noamgeller's picture

My youtube channel started to recommend me
Interviews of homeless people in LA and the surroundings...many of those poor souls are truly fascinating, illuminating even. Now stumbling on this article and the sentence contains "bargain" must means that something is really rotten with us humans. Shame, shame on us, truly ):

RobertSlavin's picture

I just want someone from the Dan D'Agostino company to explain why this is a reasonable price for this pair of amplifiers.

The reviewer should have asked the company this question. But Serinus never asks this basic question of the manufacturers of the many expensive products he reviews. Price is a very important consideration in a review of a product but not one he seems to pay attention to.

TJ's picture

Congrats JVS on the successful outcome of your AC rewiring project (!) and thank you for this fine review. As a long time Krell user, I’m always intrigued to see what Mr. D’A is doing next.

As compelling as the SQ of his latest amp must be, I can’t help but wonder how it would compare to an SPL s1200, or even the smaller s800 which I am listening to as I write this. These amps have an interesting gain stage with 120V rails, a minimal number of output transistors in a cascode configuration and exemplary build quality. Their surprising clarity, stage depth and deep bass are even more interesting. Definitely worth a listen if you have the opportunity.

MZKM's picture

The Rotel Michi M8 is more my aesthetic, is <1/5th the price, has less distortion and a ton more wattage.

I would like to see the people for who this aesthetic is for.

Anton's picture

This amp would look perfect in Admiral Harriman Nelson's quarters on the USOS Seaview!

Maybe even better in Captain Nemo's rec room on the Nautilus!

It's got more of a seapunk look than a steampunk, but that is just a matter of nuance!

georgehifi's picture

Doubt any Class-D could ever match this kind of BJT powerhouse.

Real amplification for those nasty hard to drive of speakers which only sound stunning when driven correctly.

Cheers George

Jason Victor Serinus's picture

As I prepare to start coverage of T.H.E. Show on Friday, I see multiple comments about the term "bargain" and scratch my head. This is not a term I used in my review. Nor is it a word that I would ever apply to monoblocks that cost almost $80,000/pair.

Products cost what they cost. Those who can pay the price enjoy them; those who cannot have alternatives. The Rotel Michi, mentioned above, is a product I also reviewed in stereo form and praised highly.

jason victor serinus

Ortofan's picture

... decade, DDMAS did offer an entry-level "bargain" stereo amplifier in their version of a plain, black box. The sole front panel adornment was a copper plate bearing the engraved signature of its creator. The Classic Stereo amp then sold for a mere $13,500.

That model is no longer in the current product line-up. The entry-level stereo amp is now the Progression S350, for about $27K. Apparently, DDMAS customers are unwilling to forgo the fancy chassis and the ostentatious power meter.

haroon's picture

John; kindly explain the distortion spikes that coincided with the zero-crossing points in the signal's waveform. Where is that, "more class-A goodness" in this new version?

John Atkinson's picture
haroon wrote:
John; kindly explain the distortion spikes that coincided with the zero-crossing points in the signal's waveform. Where is that, "more class-A goodness" in this new version?

Yes, the second-harmonic waveform is overlaid with spikes at the sinewave's zero-crossing points, but the level of the distortion is still very low, at 0.029%.

As the Momentum 400 MvX runs very hot, I suspect that the designer adjusted the output stage's bias current to ensure that the amplifier didn't overheat.

John Atkinson
Technical Editor, Stereophile

David Harper's picture

why is this forum so dead? Is it because most people have outgrown interest in audio gear? I'm asking a legitimate question. Or maybe young people just don't understand why anyone would care more about gear than about music? This hobby (if that's what it is) is dying. We are an anachronism. Not that I care. Change is inevitable. But it is an interesting question isn't it.

stereostereo's picture

All questions could be somewhat interesting based on their validity. Maybe you care about the gear more than the music but that has not been my experience based on my audio retail store. At my most recent Woofers and Whiskey event I had over 30 people here between the ages of 15-23. And more than 50 between the ages of 25-40. And the main driver has been overwhelmingly ones love of music. I stress to the industry folk who help me with these events to "just play music and have fun." No discussion of crossovers or woofer materials. And people have really responded and the discussions usually center around The Beatles, Frank Sinatra, Frank Ocean or Frank Zappa. That ain't about a hobby it's about a passion for music. And honestly I have not seen that much change in our industry. Sure the gear has gotten better, prettier, Hi res audio, etc but the one element that has remained constant is our passion for music. And that will never change.

Glotz's picture


Anton's picture

700,000 plus visits per month, dead or not dead?


On the other hand, Audio Science review gets 1.3 million plus.


Absolute Sound, 390,000


I guess the question is how 'lively' qualifies as not 'dead?'

Glotz's picture

And yet no response to your circulation figures as an "I'm wrong, sorry."

If he went to an audio show he would see that the places are jammed with tons of people with a variety of backgrounds and ages... and spending levels.

Time to come out of the house, dude. There's a whole world out there! And it's FUN!