Dan D'Agostino Master Audio Systems Progression M550 monoblock power amplifier Page 2

After a brief listen, Bill encouraged me to try setting up the Progression M550s and Momentum HD preamp the same way they're set up at D'Agostino's Arizona factory, with the electronics resting on their attached rubber feet. I'd always preferred the effects of aftermarket supports to those rubber feet, but those that sounded best had been discontinued and returned to the distributor. I was curious to learn if returning to the rubber feet might help address some longstanding issues in my system.

During my first listens after Bill departed, I discovered that the lower midrange had lost its customary focus. Thinking back to my chats, at T.H.E Show 2021 in Long Beach, with Norman D. Varney of A/V RoomService, I decided to try his EVP (Equipment Vibration Protectors) under the Progression M550s. Varney, who subsequently paid a visit to Port Townsend after spending time at NWAA Labs in Elma, Washington, designed the electrical grounding/isolation setup for George Lucas's Skywalker Ranch Scoring Studio and touts accredited acoustic lab measurements to back up his claim of the positive effects of his EVP's effectiveness at isolating equipment from vibration.

The A/V RoomService EVPs, together with the HRS DPX-14545 Damping Plates I'd used on the original Progressions, did more than resolve all lower midrange mush; they also helped smooth out some longstanding rough edges in my system without adding brightness, glare, or other coloration. I've continued to experiment with ideal placement of the EVPs, which I use on many components, digital and analog, that are not supported by Wilson Audio Pedestals.


Time for listening
Once those setup issues were resolved, I was a happy camper as I noticed at once the M550's ability to convey subtle details. In-breaths were more evident on Rickie Lee Jones's marvelous take of the Stones' "Sympathy for the Devil" (Tidal, 16/44.1 FLAC), from her album The Devil You Know, and the transition from soft singing to whisper was more impactful. On the line, "I killed the Czar and his ministers," I discerned a sly change in tonal color that had never come through before—nor had I noticed places where RLJ intentionally lags a bit behind the beat.


On the fabulous Catherine Russell and Wynton Marsalis take of "Make Me a Pallet on the Floor," arranged by Marsalis for the movie Bolden (24/96 FLAC, Qobuz), I heard more subtlety and shading to the cello—more of the stuff that distinguishes a rendition as special. On a very different recording, of the significantly higher-voiced and radiant Elly Ameling sparkling her way through Schubert's "Die Sterne" (The Stars) with Dalton Baldwin on piano, from The Artistry of Elly Ameling (Tidal and Qobuz 16/44.1 FLAC, Philips 473-4512), the voice floated in space like I'd never heard it before, and the bass line of the accompaniment, which isn't superbly recorded, was clearer. Similar distinctions of detail and presentation surfaced on Mahler's anything-but-subtle Symphony No.3 performed by Iván Fischer and the Budapest Festival Orchestra (Channel Classics DSD128). On this recording, pitches were clearer on divided horns, and the "burr" on horns was more discernable. Timpani sounded clean and strong, and the lowest-pitched lines of the double basses were clear, solid, and substantial.


Another big ear-opener arrived when I transitioned between files of two recently reviewed DXD recordings: Sono Luminus's Northscapes from pianist Ieva Jokubaviciute and 2L's Solacium from Trio Mediaeval. The latter is encoded in MQA, but I believe that different environments, microphone placement, and engineering accounted for 2L's markedly lower noisefloor. I listened intently when I reviewed both these recordings with the original Progressions, but I'd never heard such huge distinctions in background noise.

The sound of the new monoblocks was in the same family as the original Progressions but warmer, with a subtle glow and smoother finish that produced rounder images. There was an unmistakable similarity to the beautifully finished sound of the other amplifiers I've reviewed with either pure class-A or significant amounts of power in class-A, notably the Pass Labs XA200.8 monoblocks, Gryphon Essence monoblocks, Krell K-300i integrated, Audio Research 160M monoblocks, and Doshi Evolution monoblocks. You may not be surprised to learn that these are the best-sounding amps I've reviewed over the past half-decade.


When I reviewed the relatively low-powered Gryphon Essence monoblocks, the recording that allowed them to steal my heart was the late Lorraine Hunt Lieberson's mesmerizing live rendition, with pianist Roger Vignoles, of Mahler's "Ich Bin Der Welt Abhanden Gekommen" ("I am lost to the world") from the Five Rückert-Lieder, as preserved on Lorraine Hunt Lieberson: Mahler, Handel & Lieberson (Wigmore Hall Live, Tidal 16/44.1 FLAC). It's a remarkable recording—one that makes Wigmore Hall sound much better than the two times I sat in the hall's less-than-prime seats during a 2019 trip abroad.

Listening through the D'Agostino Progression M550 monoblocks, what impressed me most (besides the beauty of Hunt Lieberson's voice and her total identification with music and text) was the Progression M550s' ability to convey the inner warmth and depth of someone transported. I was equally struck by the clarity of a piano recorded in a surprisingly quiet and exceptionally dimensional acoustic. The silence was as astounding as the heart that shone through this great artist's voice. When an amp can deliver all that from a simple performance with voice and piano, it's a great amp.

Progress(ion) report
With my assessment presumably complete, I implored husband David and audiophile buddy Scott Campbell to help me move monoblocks back and forth for direct comparisons.

On my trusty deep bass electronically hyped standby, Boris Blank's "Electrified II" from Toy (24/48 MQA FLAC, Tidal), the original Progression Monos sounded splashier on Malia's vocals. There was less color differentiation, soundstaging was less awesome, and the presentation seemed plainer, flatter, and less muscular and dynamic. Returning to Elly Ameling's smaller-scale recording, her voice seemed to lose some warmth and radiance. There was less silence around the voice and less three-dimensionality. Listening was less involving.

One of my go-to recordings for color, depth, microscopic detail, expansiveness, and dynamic contrast is Anna Thorvaldsdóttir's Metacosmos, performed by the Iceland Symphony Orchestra on Sono Luminus's Concurrence (24/352.8 WAV, DSL-92237). Thorvaldsdóttir places great significance on the emotional impact of a single instrument, briefly singing its own song like a bird in the distance as many dozens of others issue their own calls. The original Progressions smudged such details with clatter, occasionally burying them entirely. When everything started going at once at higher volume, they struggled to separate one instrument from the other. They also sounded less rich, with less gratifying inner warmth and contrasting colors.


In addition to their far blacker space between notes, greater resolution of small details, and natural-sounding illumination, the Progression M550s consistently wowed me with their dynamic mastery. Early in Metacosmos, where low bass rumbles are suddenly interrupted by a loud, sharp crackle, the familiar entry was so powerful that it startled me. Later, when every instrument and its mother started playing at once, the M550s nailed the brutal force and savagery like no other amp I've ever heard in my system. The original Progressions struggled to separate one instrument from the other, and small details were buried amidst the din. I was shocked by the cumulative impact of the differences between old and new Progressions.

From great to "gaaah!"
With the Progression M550s back in place, all notes taken, and my listening presumably complete, I set about enjoying myself. Everything was smooth sailing when Daryl Wilson emailed that he finally had enough stock of the new Wilson Audio Acoustic Diode Spikes ($3200/set of eight or $3000 when ordered with current speaker models) to send some to try under the Alexia 2s. The Acoustic Diodes (AD Spikes), which come standard on Wilson's Alexx V loudspeakers, were designed with the same laser vibrometer testing equipment that was employed in the development of the Wilson Pedestal equipment supports and benefited from the research that was essential for the Pedestal's creation.

I then enlisted the assistance of Gary Bruestle, one of Definitive Audio's speaker setup wizards, to help attach Acoustic Diodes to the Alexia 2s. Since that required releveling the speakers, I felt that the significant changes I'd made to electronics, acoustic treatment, rack, and supports since the Alexia 2s arrived years ago mandated a reassessment of speaker position.


Keeping the speakers in their original position, we installed the Acoustic Diodes. The soundstage widened, detail and texture became more discernable, and bass grew clearer and more defined. The impact of better amplification and superior loudspeaker spikes became evident on the Kronos Quartet's performance of Terry Riley's Sun Rings (24/96, Nonesuch 587972), which I wrote about for My Back Pages in the August 2020 issue. Even though I thought the recording pretty damn special to begin with, I heard a wider and more coherent soundstage coupled with more far more detail, layering, and silence. At the risk of sounding like an infatuated teenager, the sound was awesome. No wonder Leslie Ann Jones and her fellow engineers won a Grammy for this recording.

Next, we repositioned the speakers several inches closer to room center while keeping them the same distance from the front wall. And that's when we discovered that left and right channels sounded different from each other. From the left came warm, color-saturated, extended sound; the right sounded surprisingly flat and rolled off on top. Given the large opening to the hallway on the left side of the music room, I'd expected some differences between channels, and measured the same during my Accuphase DG-68 Digital Voicing Equalizer review. Was that what I was hearing, except far more clearly now that the speakers had been repositioned?

After lots of cable and channel swapping, and many left/ right balance checks while playing part of Hindemith's Symphonic Metamorphosis on a brightly recorded Mercury Living Presence monaural CD compilation featuring Antal Dorati, Rafael Kubelik, and the Chicago Symphony Orchestra (16/44.1 WAV, ripped from Mercury 289 534 397-2), the evidence was incontrovertible: I had two very different sounding M550s. As confident as I was that the more extended and tonally rich amp had determined the majority of what I'd heard during my evaluations, something was clearly amiss.

Following late-night phone consultations with Editor Jim Austin, I awoke to speak with Bill and Dan about the possibility of delaying the review and sending the amps back to Arizona for repair. Dan, though, was certain that the amps were fundamentally sound. He thought the discrepancy was caused by a shift in biasing, which presumably happened during shipment.

Two tension-fraught days later, Hans Brackmann, Definitive Audio's store manager, drove to Port Townsend to rebias the amps. All D'Agostino dealers are prepared to rebias the M550s whenever necessary.

Sure enough, rebiasing was called for—just that, nothing more. By the time Hans left, both channels sounded the same (save for minor discrepancies caused by room imbalances), and I heard even more of the beautiful, smooth, finely detailed, impeccably controlled, remarkably dynamic, slightly warm and glowing sound that had made me fall in love with the Progression M550s.

So . . .
Once the Progression M550s were optimally set up and biased, love at first listen morphed from an infatuation into a relationship.

For anyone who values colorful and glowing amplification that brings natural timbre and the subtlest of details and dynamic shifts to the fore while supplying a breathtakingly full measure of big-picture dynamics, slam, and top-to-bottom frequency response, the Progression M550s must be heard. They are wonderful amps.

Dan D'Agostino Master Audio Systems, LLC
5855 E Surrey Dr.
Cave Creek, AZ 85337
(480) 575-3069

Jeffreylee's picture

Let me get this straight. Serinus reviewed a $45,000 pair of amps and didn't notice that one of them wasn't working properly THE ENTIRE TIME? This guy has turned into an ongoing source of embarrassment and if it wasn't for Mike, Herb and Ken I would have canceled my sub strictly because of his incompetence, not to mention his elitism. This review should have been shelved and rewritten, preferably by someone else, until both amps were working properly.

John Atkinson's picture
Jeffreylee wrote:
Let me get this straight. Serinus reviewed a $45,000 pair of amps and didn't notice that one of them wasn't working properly THE ENTIRE TIME?

It's probable that the output-stage bias of one of the amplifiers, slowly drifted while he was using the pair. It was only when he started his auditioning anew with the repositioned Wilson speakers that he noticed the problem with that amplifier.

John Atkinson
Technical Editor, Stereophile

Jeffreylee's picture

With all due respect, that explanation doesn't seem to scan -- unless bias can drift in a matter of minutes. Serinus clearly says that everything was fine until the speakers were moved, which probably took 30 minutes given their size. And then there's D'Agostino's belief that the bias drifted during shipment. Stereophile has always had some writers I trust more than others but this is pretty ridiculous.

John Atkinson's picture
Jeffreylee wrote:
With all due respect, that explanation doesn't seem to scan -- unless bias can drift in a matter of minutes. Serinus clearly says that everything was fine until the speakers were moved, which probably took 30 minutes given their size.

If the bias had slowly drifted during his auditioning, the incremental change in sound quality would have been difficult to perceive. (Think of the "frog in water that is slowly heated" analogy.) It was after the amplifiers were turned on again after the speaker moving that JVS realized that something was not right.

Props to JVS for his honest disclosure.

John Atkinson
Technical Editor, Stereophile

MFK's picture

The second sentence of Jeffreylee's first post nails it. However, we should be grateful for JVS's music choices and reviews. They have led me to a lot of wonderful music that I likely would not have heard otherwise.

Jim Austin's picture

I want to leave the substance of this comment intact, but I dislike the incivility; I've deleted two other comments for precisely this reason. But I can't think of how to perform surgery on your comment while ensuring that it remains your own, so I'll leave it alone. (No promises, though, about future comments.)

I'm also leaving it because it provides a good opportunity to respond.

I believe that a few critical readers, including you, are missing two points. Or maybe it's three. The first is that we're being radically transparent. For good or bad, instead of covering our collective ass, we've left this out there for all to see. The decision here was to present the whole process, good and bad, so that people can judge for themselves.

I think Jason was courageous for putting this out there--these uncivil responses prove that point. Perhaps I was wrong to allow him to do so, and yet I think it was the right thing to do.

After all, he didn't miss the biasing issue. He heard it eventually. Many writers--specifically writers at other publications--would doubtless have reworked the story to make themselves look better. Jason is to be commended for his honesty and--that word again--transparency.

The second point is this: There is no reason to assume that this was an abundantly audible effect. It may have been quite subtle. You weren't there. Neither was I. Such things can easily be swamped by room, stereo, and (other) psychoacoustic effects, especially when listening in stereo. There's a reason that at Harman and some other places it's standard practice to listen to just one speaker. We audition in stereo because that's how people listen to music, but one speaker can easily mask what's happening with the other. It certainly is possible, if not likely, that I could have missed it.

Either way, we told the truth.

Jim Austin, Editor

MatthewT's picture

The harshest critics didn't read, or at least cherry-picked, as it was all there in the article warts and all from the start. JVS takes more crap than anyone, all the more reason for him to write more.

tonykaz's picture

My older brother was a Horn Player for the DSO.

I recall one performance that seemed wonderful to me, I'd heard him practice that music for a Month.
He got a serious ass chewing for missing a few notes which he fully realised and expected.

The Audience never noticed anything amiss. Me included.

People's synapses adapt and adjust.

That is what makes MR.JA's laboratory work so very important.

Tony in Florida

tonykaz's picture

Are you gonna own these Mono Amps ???


Can I buy your old, tired & worn outs ?

I'll send a Wooden Ship builder to pick them up!

Tony in Florid

rickayre's picture

are you gonna trade in your current amps?

tonykaz's picture

I got first dibs on these tired & warn out old pieces of sadness.


I'll give you first right of refusal for a couple thou. $2,000.

I can't quite estimate a Final Sale Price because they once belonged to a Famous Reviewer for the World's greatest Publication.

Expect them to sell for about 125% of original Retail... of course they both will be properly Autographed and accompanied with beautiful Framable Photos .

You'll be getting the bargain of the Century.

Tony in Florida

ps. for a small additional few thousand dollars I'll try to entice both Mr.JA1 & JA2 to Sign em.

pma's picture

The strange distortion vs. amplitude plot that you can see here
speaks for itself - it is a medium biased class AB amplifier with very low feedback factor or no global feedback at all. Then you see the rise of distortion above 1W and a minimum near to 200W, because the crossover area and distortion compared to the high output voltage gets relatively lower. Shame on the designer.

This and similar amplifiers are its own category with "special" customers. They do not care about measurements at all and probably would not hear any problem. John Atkinson stays too much on a polite side in my opinion, this should be clearly condemned how poor is the result.

tabs's picture

I posted something in response to the glaring deficiencies of this equipment, and it very much appears Stereophile staff deleted it. In no way did I use any foul language, and in terms of spirit, I was no more personal in my attack than @Jeffreylee who rightly called JVS an embarrassment and received a reply from JA instead of a deletion.

Jim Austin's picture

... you referred to another forum member as "a cancer."

Jim Austin, Editor

Jim Austin's picture

Your assertion that anyone is "stealing money" from anyone is of course ludicrous. People who buy D'Agostino equipment (and equipment from other expensive brands) do so with eyes wide open and all their faculties about them. I'm sure their enthusiastic customers would be amused at your presumptuousness.

Jim Austin, Editor

partain's picture

" a conspiracy of audiophiles " is at least as good as " a murder of crows " .

Jim Austin's picture

Jim Austin, Editor

thatguy's picture

what causes bias to drift in a new amp?

Jim Austin's picture

Due to the uncivil nature of some of the posts, this article has been closed to further comment.

Jim Austin, Editor