Dan D'Agostino Progression Mono monoblock power amplifier

For as long as I've known about high-end audio, I've put Dan D'Agostino, co-founder of Krell, on the same pedestal reserved for the likes of Frank McIntosh, Saul Marantz, Avery Fisher, H.H. Scott, and Sidney Harman. The reason is simple: Dan's the man whose achievements at Krell led me from the harsh sound of my first high-end amp into another dimension, one of truly musical sound reproduction.

I still recall the layout of the room where I first met D'Agostino—at an audio show, years before I began writing for Stereophile. I introduced myself in a trembling, fan-boy voice. (I did the same with John Atkinson.) Not many years later, when I found myself the owner of a Krell KSA-50S, its imaging blew me away. While the amp didn't entirely meet my needs, my Krell experience only deepened my appreciation for D'Agostino's work.

At the end of 2009, Dan and Krell's cofounder, Rondi D'Agostino, were forced out of the company by what Dan terms a "hostile takeover," but he wasted no time in founding Dan D'Agostino Master Systems. The company soon released a series of expensive Momentum amplifiers and preamplifiers, whose sound and distinctive "audiophile jewelry" enclosures further solidified his reputation as a cutting-edge designer (footnote 1). Now comes the less expensive but hardly plain-Jane Progression series.

The moment I heard the first pre-production pair of Progression monoblocks ($38,000/pair), driving Wilson Audio Alexx loudspeakers at Definitive Audio's 2016 Music Matters event, I wanted them to be the first amps I would review for Stereophile. Alas, when D'Agostino's longtime associate Bill McKiegan visited my home to install the first pair of Progression monoblocks manufactured in their initial, limited production run, technical problems intruded: First, a loose ribbon cable in one monoblock's chassis caused it to emit a loud noise. Although McKiegan easily reattached the cable—its new header and pin should prevent future problems—both monoblocks continued to emit an annoying hum that made listening a chore, and compromised all sound above the bass region. This second problem was traced to improper potting in the transformers, an error on the part of the transformer provider, and has since been addressed. Still, it took five months before a replacement pair of Progressions could be freed up for review.

Appearance and Design
The Progression's enclosure and chassis—in this case, the same thing—is machined from a solid billet of aluminum. Most visually striking are a large, round, copper-rimmed, green-lit power-output meter—it dominates the front panel—and, running along both edges of the top plate, the large holes that replace heatsink fins.

The handsomely designed user manual says that the meter is "driven by a high-speed ballistic circuit that enhances the meter's responsiveness" and allows it to cover the amp's entire output range. As I listened to high-resolution recordings while sitting 12' back from my speakers in my 20' by 16' by 9' listening room, the needle didn't rise very far, even when I raised the volume to the point of discomfort and every instrument in an orchestra or band was blaring simultaneously. Since I have no desire to stop working for Stereophile, I never tried to find out if my CDs would fall off their shelves before the needles pegged.

Secreted directly under the meter, on the bottom edge of the Progression, is a small, easily accessible On/Standby button. Assuming that these class-AB amps would consume little electricity when music wasn't playing, I left them on 24/7 to keep them ready for listening, instead of having to wait half an hour for them to reach optimal operating temperature. Even when I spent several hours listening nonstop to complex music with lots of dynamic peaks, the Progressions never got more than warm to the touch. On colder days, I still needed to heat the room.

On the Progression's rear panel are a 20-amp IEC inlet, a large main power toggle switch, a single balanced (XLR) input—there's no unbalanced input—and two speaker binding posts that are fairly easy to screw down tight. The large space between cable connections makes it easy to keep wires apart. There are also 12V on/off trigger input and output switches for use with other components (I never used them), and a toggle switch for adjusting the brightness of the power meter (Low/Off/On). I liked the green glow, and left the meter on.

1017dagprog.bac.jpg

D'Agostino believes that great sound reproduction requires power. Thus, the Progression's chassis contains a very large, 2.5kVA power supply claimed to deliver plenty of reserve power for peaks in loud rock and classical. D'Agostino says the amplifier "easily" delivers 2000W into 2 ohms. "The Progression . . . will play loud, but it is the control of the speaker drivers I was after," he wrote in the manual. (To learn more about the Progression and Dan D'Agostino, see "Dan D'Agostino's Progress to Progression" elsewhere in this issue.)

Listening
When the replacement Progressions arrived, Bill McKiegan returned to ensure that they were working properly. (They were driven directly from the analog outputs of my dCS Rossini DAC.) Normally, when company reps help install gear, Stereophile reviewers thank them for their time but keep their critical impressions to themselves. But I'm a Cancer—an emotional being. Thus, when we put on a familiar SACD of Iván Fischer conducting the Budapest Festival Orchestra in Mahler's Symphony 9 (Channel Classics CCS SA 36115), and the stone-cold Progressions delivered far more believable air and sense of hall boundaries than any other amps I've heard in my reference system, I found it difficult to mask my excitement.

At first, I began my tests with a wide assortment of familiar fare. Yes (check), that eccentric collection of percussion in Lou Harrison and John Cage's Double Music, with Angel Gil-Ordóñez conducting the Post-Classical Ensemble (24-bit/48kHz WAV file, Naxos 8559825), sounded as tight as could be. There was believable body to the sound, and maximum color differentiation between the composers' crazy collection of standard and repurposed percussion instruments. And, yes (check), the final track on Ludovic Morlot and the Seattle Symphony's excellent recording of Stravinsky's The Rite of Spring (SSM 24/96 WAV file, Seattle 1005) sounded equally outstanding. Not only did the Progression Monos nail the savagery of the high-driving piccolos and brutal bass without breaking a sweat, they also kept every instrument in control and balance while conveying a realistic, airy soundstage and thunderous percussion.

One other thing about the Progressions struck me from the get-go. Perhaps owing to their speed and reserve power, contrasts between soft and loud in hi-rez orchestral recordings were greater and more impactful than with any other pair of monoblocks I'd heard in my reference system.

Turning to Murray Perahia's performance, on piano, of Handel's Harpsichord Suite in E, HWV 430 (CD, Sony Classical 62785) left me marveling that, for the first time with any amp in my system, I could hear the resonant space around the piano, and sense the size of the space captured by Sony's engineers. I also noted that while the sound was just a touch on the warm side of neutral, the tonalities were beautiful, and the piano's bottom notes sounded more realistic than I'd ever heard them in my system.

Not only did the Progressions clearly convey Perahia's perfect, rapidly articulated runs in the suite's final, joy-filled Air with five variations, it also depicted those notes as connected in a continuous, supremely musical flow. As I've discovered in listening to this recording countless times at audio shows, some amps overemphasize the spaces between notes, making them sound a bit like machine-gun fire, while others blur the notes together. The Progression made Perahia's playing sound as musical and technically astounding as it would in real life.

"I love this recording as if new," I scribbled in my notes. "Everything sounds fabulous."



Footnote 1: See Michael Fremer's reviews of the Momentum preamplifier and power amplifier here and here.
COMPANY INFO
Dan D'Agostino Master Audio Systems
PO Box 89, 7171 E. Cave Creek Road, Unit K
Carefree, AZ 85377
(480) 575-3069
ARTICLE CONTENTS

COMMENTS
georgehifi's picture

Agostino Progression Mono monoblock:
"Consequently, the Progression's reproduction of a 10kHz squarewave (fig.2) featured very short risetimes with, commendably, no overshoot or ringing apparent."

Linear Tube Audio ZOTL40 Mk.II power amplifier:
Read more at https://www.stereophile.com/content/linear-tube-audio-zotl40-mkii-power-...
"the response extended very high, not reaching –3dB until 120kHz, this correlating with the superbly defined shape of a 10kHz squarewave into this load (fig.2). A slight amount of overshoot is visible in this graph, though there is no ringing."

These are great to see, and it's great that from the comments they're appreciated by the measurement team and readers alike.

Though when Class-D amps are measured, they normally have horrendous looking square waves, but these days Stereophile use low power special bench test filters to filter them so they look good to the readers. This is not representative of what's being sent to the speaker in normal everyday use.
This is from the days when Stereophile didn't use the "special" filters, to show what's really coming out the speaker terminals. I believe it should go back to this.
https://www.stereophile.com/images/archivesart/805CIAfig2.jpg

Cheers George

a.wayne's picture

John, NPR ! not surprised all that RF hash did you in ... :)

Ortofan's picture

... "musical"? Is it the non-flat frequency response into a typical loudspeaker load? Is it the series of distortion products that are up to 20dB above the noise floor of a CD, let alone that of a higher bit-rate recording?

Why not perform a Hafler type straight wire differential test test on every amp that comes in for review?
https://www.stereophile.com/content/manufacturers-comment-0

Or a level-matched A/B comparison as demonstrated by Harbeth's Alan Shaw: https://vimeo.com/137001237

Perhaps a direct comparison with the Rotel RB-1590?
http://www.bwgroup.ch/wp-content/uploads/2016/11/Hi-Fi-News-11-2015-Test...

John Atkinson's picture
Ortofan wrote:
Why not perform . . . a level-matched A/B comparison as demonstrated by Harbeth's Alan Shaw: https://vimeo.com/137001237

See my fairly recent writing on such tests at www.stereophile.com/content/simple-everything-appears-simple.

John Atkinson
Editor, Stereophile

Ortofan's picture

... exceedingly straightforward.
Match the input sensitivity of the two amps being compared using a test tone and a voltmeter; find the clipping point of the lower powered amp (and then keep the input volume for both amps below that level); then switch back-and-forth between amps at will.
Is there something he's missing?

Have you considered acquiring one of the Audio by Van Alstine ABX Comparator units and having the Stereophile reviewers give it a try?
https://www.dagogo.com/audio-by-van-alstine-abx-comparator-review-part-1...
https://www.dagogo.com/audio-by-van-alstine-abx-comparator-review-part-2...
https://www.dagogo.com/audio-by-van-alstine-abx-comparator-review-part-3...

John Atkinson's picture
Ortofan wrote:
Mr. Shaw makes the comparison testing seem exceedingly straightforward. Match the input sensitivity of the two amps being compared using a test tone and a voltmeter; find the clipping point of the lower powered amp (and then keep the input volume for both amps below that level); then switch back-and-forth between amps at will. Is there something he's missing?

Yes, such testing tend to produce false negatives, ie, not detecting a difference when one actually exists. So unless you want to "prove" that no differences exist, they are no more useful than sighted listening. I do admit, however, that the latter tend to produce false positives.

Ortofan wrote:
Have you considered acquiring one of the Audio by Van Alstine ABX Comparator units and having the Stereophile reviewers give it a try?

I tried out the original ABX box 30 years ago and found, for example, that I could identify absolute polarity with statistical significant certainty. I have also identified amplifier differences under blind conditions, even differences between series capacitors of different types. Yet those results were all dismissed by the proponents of blind testing. So what would be the point in repeating all that work? No-one would be convinced by the results, on both sides of the debate.

John Atkinson
Editor, Stereophile

Ortofan's picture

... determined to be statistically significant, then on what basis were they dismissed?

Would no one at all be convinced by the results of blind/level-matched comparisons? There are probably those readers who pay no heed to the test measurements you publish, yet you expend the time and effort to make them. Results of an AB(X) test would provide additional input to the evaluation/decision process for those who might place some value on the outcome.

Lastly, Harbeth's Mr. Shaw has a standing offer of a free pair of his speakers to anyone who can distinguish between two amplifiers in a blind/level-matched comparison. Have either you or one of the reviewers on your staff considered taking him up on his challenge?

John Atkinson's picture
Ortofan wrote:
If the results of your ABX comparison trials were determined to be statistically significant, then on what basis were they dismissed?

Because the results were contrary to what so-called "objectivists" believed. Demands for reviewers to participate in blind testing come from those who want such tests to "prove" there are no audible differences.

Ortofan wrote:
Results of an AB(X) test would provide additional input to the evaluation/decision process for those who might place some value on the outcome.

Did you not read the article linked in an earlier posting of mine? Performing a blind test that produces legitimate results when there are small but real audible differences is not a simple matter. And if no-one takes any notice of the results if they conflict with their beliefs, what would be the point?

BTW, my opinion is formed by having taken part in more than 100 such tests as organizer, proctor, and test subject since my first in 1977. I think it fair, therefore, to ask how many tests you have taken part in to be so sure of their efficacy?

Ortofan wrote:
Lastly, Harbeth's Mr. Shaw has a standing offer of a free pair of his speakers to anyone who can distinguish between two amplifiers in a blind/level-matched comparison. Have either you or one of the reviewers on your staff considered taking him up on his challenge?

I don't see any benefit in participating in Mr. Shaw's marketing.

John Atkinson
Editor, Stereophile

John Atkinson's picture
John Atkinson wrote:
Ortofan wrote:
If the results of your ABX comparison trials were determined to be statistically significant, then on what basis were they dismissed?

Because the results were contrary to what so-called "objectivists" believed. Demands for reviewers to participate in blind testing come from those who want such tests to "prove" there are no audible differences.

For more on this denial of facts by believers in "scientism," see this essay I wrote 23 years ago: www.stereophile.com/asweseeit/894awsi/index.html.

John Atkinson
Editor, Stereophile

Ortofan's picture

... I've been involved with approximately one blind/masked test per year - though never with consumer grade audio equipment. Whether the outcome is as expected or not, the methodology has proven useful as a means to preclude certain factors from influencing the results of a comparison test. If you doubt the validity of such a testing protocol, by what other means might you suggest eliminating such factors as unmatched levels, knowledge of the brand identity and product appearance from potentially influencing the outcome of a comparison test?

John Atkinson's picture
Ortofan wrote:
On average, during the past four decades I've been involved with approximately one blind/masked test per year - though never with consumer grade audio equipment.

Thank you. My experience of those who demand blind tests of reviewers is that they have never taken part in such tests so have an uncritical belief in the results of such tests. You are a rare exception.

Ortofan wrote:
Whether the outcome is as expected or not, the methodology has proven useful as a means to preclude certain factors from influencing the results of a comparison test.

Of course. But without additional testing you have no idea if your blind test protocol is sufficiently sensitive to detect small but real differences. If, for example, your test cannot detect something that is known to be audible, such as a 1dB difference in level, then any results it produces will be meaningless. There must have been interfering variables that you have not accounted for. One such is even the fact that the listener's mental state in a test is different from what it is in conventional listening. I mentioned this in the articles of mine that I have linked in earlier responses, which I assume you have read. If you have not, then please do so.

Ortofan wrote:
If you doubt the validity of such a testing protocol, by what other means might you suggest eliminating such factors as unmatched levels, knowledge of the brand identity and product appearance from potentially influencing the outcome of a comparison test?

Level matching is trivially easy. Knowledge of the brand is not that important for professional reviewers because they audition so many products over so many years that they don't have a horse in the race. If you doubt that, then I have to ask why you subscribe to Stereophile at all?

John Atkinson
Editor, Stereophile

Ortofan's picture

... is a key gating factor in the process of developing a new product and the decision of whether or not to release it to production. If the test panel determines that the new product is in some manner better/preferable to (or at least discernibly different from) an existing one, then the product is more likely to get approved for production. If the test panel cannot make a statistically significant distinction, then its future might hinge on whether or not it can be made more reliable or brought to market at a lower cost than the competition.

Also, certain individuals are more or less amenable to participating in blind/masked comparison testing, so you use multiple subjects. Likewise, their mental state can vary from day to day, so you conduct multiple trials.

Agreed that level matching (of electronics at least) is a simple process - but do your reviewers always (or ever) do it? With digital disc players and DACs it's not uncommon for the output from a 0dBFS input to exceed a nominal 2.0V level.

Continued interest in Stereophile is because you still conduct and publish the results of objective tests. For example, I'd prefer to spend $3K (or $6K for a bridged pair) for an amp that measures like the Benchmark AHB-2 rather than an order of magnitude more for this particular one, whose measurements, IMO, leave significant room for improvement.

mauidj's picture

when I read stuff like this...

"I also began to realize that while my reference Pass Labs XA 200.8 monoblocks sound gorgeous, and convey a special glow around the edges of each note, the Progressions illuminated each note from within."

Is it just me?

JoeinNC's picture

No, it’s not just you.

supamark's picture

he has synesthesia. I do, and sounds have palpable textures to me with some visual as well. For example, in a nice live hall, reverb tends to have an enveloping syrupy quality to me (denser reverb, thicker syrup) with a bit of visual glow (color and intensity dependant on how bright and dense respectively the reverb is).

Maybe you're simply mocking what you don't understand, and that's really not a good look.

tonykaz's picture

The Electro stuff was gorgeous sounding, I don't know why, I'm an engineer, my partner was an engineer.

But that Electrocompaniet could make our big Thiel CS3 play beautifully, much more beautifully than any other gear we ever got our hands on.
We couldn't get the Krell stuff but I had access to the Krell people who supplied me with the Koetsu Phono Cartridges. The only Electro Sales I lost were to Krell Amps.
Even Michael Jackson and Quincy Jones were Electocompaniet lovers.

Gosh darn it, some electronics make your music system sound superb. Now, we are realizing PrimaLuna stuff is like that. Go figure.

There's mediocre ho-hum stuff and there's certain pieces that are way too good to be true but true they are.

A good way to tell which is which is to look at eBay used prices for gear. The Krell stuff holds it's price well, so does Schiit stuff.

Tony in Michigan

ps. I'm waiting to learn if Jason decides to have this pair of Amps or keeps his Pass

foxhall's picture

My very first exposure to high end audio was in the mid 1990's and the system a very popular combination of Apogee, Krell and Wadia. I remember the owner remarking he preferred 3 hours of warm up for his Krell amplifiers.

Has the optimal warm up time decreased with innovation? Do you think there will ever be a time when A/B amplifiers won't need warm up time?

Do some manufacturers include warm up best practices in their manuals? My Parasound Halo gear manuals don't include this type of information so I was just wondering.

Johnny2Bad's picture

Thank you, thank you, thank you Jason for your written words "...The Progression's enclosure and chassis—in this case, the same thing—is machined from a solid billet of aluminum. ..."

Finally, a journalist who gets it ... I tire of reading, in audio and other pursuits, of a product described as "billet aluminum". A billet of aluminum is a lump of metal. There is no reason to purchase one unless a lump of metal was what you wanted in the first place, versus a functional, machined device, and they can be had at much lower cost at your metal supplier versus your audio vendor or automotive performance parts reseller.

Now, if we can only banish the fictitious product, "aircraft grade aluminum" (or it's sister, the Ford Motor Company's "military grade aluminum", another product that does not actually exist), the world will be much improved.

Of course, strictly speaking, you could have left out the "solid" part, as it's redundant (by definition, all billets are solid) but I'm still going to thank you for getting it mostly right.

tonykaz's picture

This Amp chassis is made up of multiple pieces.

It's CNC machined , no big deal considering the tooling we have today. It does not have all that exotic & beautiful a surface finish on the inside.

These aluminum pieces are not heavy, making me wonder about the power transformer.

and

making me wonder if the power supply benefits from one of those $10,000+ Power Conditioners -- or -- has Mr.D'Augostino figured out how to make a power supply that's not susceptible to what ever those Power Conditioners are supposed to filter out.

And

Does this amp need one of those aftermarket Power Cords for $5,000 to help it realize it's full potential ?

And

Of course: will these Amps replace the Pass 'house' reference Amps?

Way back in 1985ish, one of my customers went and purchased a 200W. Krell Stereo Amp that took two people to carry into the guy's house. phew

I was there to see the unboxing of the Beautiful Amp but couldn't see myself carrying the Krell line, the stuff is sooooooo darn heavy and with sharp edges. ouch.

I must say that I've admired Krell but it always seemed to be "Over-kill" type of gear.

The big Chord stuff is even greater Eye Candy.

Tony in Michigan

Allen Fant's picture

J.A.

recently you had mentioned using a disc of tracks from HiFi News-
where can I get this disc? If it not avail for purchase, is it possible to get a copy that you use? I can send a blank CD-r.
Thank You

John Atkinson's picture
Allen Fant wrote:
J.A. recently you had mentioned using a disc of tracks from HiFi News-where can I get this disc?

This was in a reprint of a review first published in 1987 and the CD is long out of print. Send me an email at JAtkinson at enthusiastnetwork dot com.

John Atkinson
Editor, Stereophile

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