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April 2023

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Dan D'Agostino Master Audio Systems Progression S350 Stereo Power Amplifier Review
The Dan D'Agostino S350 amplifier makes each musical selection sound spectacular!
Review By Tom Lyle


Dan D'Agostino Master Audio Systems Progression S350 Stereo Power Amplifier Review


  Dan D'Agostino Master Audio products are not the most expensive audio components on the market, but in my opinion, their audio products are some of the best sounding high-end audio components I've ever had the pleasure of auditioning.


I was lucky enough to have the opportunity to review two D'Agostino Master Audio components in the past. In 2017, I reviewed the excellent-sounding Momentum Lifestyle integrated amplifier, which had an onboard DAC and could also be used as a streamer with its front-panel LCD metadata display. Also in 2017, I reviewed D'Agostino Master Audio System's Momentum phono stage, which I was highly impressed with its outstanding sound quality and very user-friendly front panel controls.


The Progression S350 has a power output of 350 Watts per channel into 8 Ohms, which doubles when used with a 4 Ohm load. The technology behind this large, very heavy amplifier is impressive, which is an understatement. The technology D'Agostino Master Audio employs to achieve its superb sound quality is outlined on its website. Still, their explanation might only be appreciated by those who either have an engineering background or audiophiles who, in the past, have been exposed to the technical terms they use.

For example, they discuss their "innovative" Super Rail circuitry, where each amplifier uses two voltage rails, a positive and a negative, which support power delivery to the speakers. The music signal passes between the two rails, but to natural loss, and this signal never reaches the amplifier's output rails' full capacity.

The D'Agostino amplifier's Super Rail overcomes this limitation by using higher voltage rails in the sections before it reaches the output stage. Boosting the voltage allows the musical signal to "exploit the full capacity of the output voltage rails Having the musical signal swing closer to the output rails "maximizes the performance of the output circuitry design itself." They conclude that this is why this power amplifier's dynamics and distortion rating is improved, and the amp has a "fierce grip" of the speaker.

Even on paper, it was evident that D'Agostino went far beyond what is necessary to make a power amplifier sound its best. This amp weighs 115 pounds for a reason, and not just because the innards of its anodized aluminum chassis contain a 2,000VA power supply transformer coupled to nearly 100k microfarads of power supply storage capacitance. Also inside the S350 is a driver stage with 48 transistors split between its right and left channels.


Do you fully understand everything in the explanation above? I understand only some of it. But what is obvious is that the constituents that make up the Progression S350 are far beyond what is inside other solid-state power amplifiers that have previously graced my system. Still, in many of the reviews I've written, I have attempted to make a joke by suggesting that if a component's sound quality is superior to others within its price class and comes with a decent warranty, I wouldn't care if the designers of this component used parts found in a junkyard, or first-year engineering students designed it.

The Progression S350 power amplifier surpassed the admittedly zany demands of my "joke" above, and spoiler alert, by having an outstanding sound quality that made listening to music an event every time I powered up the D'Agostino Master Audio Progressive S350 power amplifier. This power amp also looked exceptionally good while performing the task, with its 115-pound, 18-inch by 9-inch anodized aluminum chassis nearly 2 feet deep and a front panel that D'Agostino Master Audio claims were inspired by the look of a Swiss watch.



The amp's front panel's sizeable green-glowing power meter has two 90-degree needle swing arms and uses a high-speed ballistic circuit to enhance the meter's responsiveness. If one is going to spend this kind of money on a power amplifier, it might as well look good. And in my opinion, the D'Agostino Master Audio Progression S350 looks almost as good as it sounds.



There is much more about the technology behind this D'Agostino Progression S350 power amplifier that I'm leaving out. I could fill my allotted space only by discussing the technology behind this component. But I'd rather discuss how it sounds in my system.


I needed help carrying the Progressive S350 up the stairs to my listening room. It weighs 115 pounds and has no handles. It eventually ended up on the bottom shelf of my Arcici Suspense equipment rack. This equipment rack's claim to fame is that it has hanging shelves suspended by metal bars hanging from a 50-pound steel plate, which are supported by three user-adjustable inner tubes. The bottom shelf where the D'Agostino Master Audio S350 power amp was located is not suspended. It is a stationary shelf connected to the floor via steel spikes. If this power amplifier were a permanent member of my system, I'd likely place it next to the equipment rack on a dedicated amplifier stand.

My dedicated listening room is medium-sized, with acoustic treatments on its walls and shelves filled with LPs around its perimeter. Two dedicated AC lines run directly to the circuit box in our basement. The wall receptacles were replaced when we moved in about 15 years ago with cryogenically treated models made by a Canadian company Virtual Dynamics, which has since ceased operation.


For the past few years I've been using Kimber Carbon 8 interconnects throughout the system, except for the USB cable a Wireworld Platinum Starlight USB. For the past month or so, I've been using a cable made by a small company in Oklahoma City called Timbre, their Timbre Argentum line that uses solid silver conductors, a Argentum Balanced between the amp and preamp, and their Argentum Speaker between the amp and speakers.

The digital front-end of the system uses a computer-based music server with its USB output connected to the USB input of an EMM Labs DA2 converter. I sometimes used a Benchmark Media DAC 3 HGC DAC in place of the EMM Labs converter - just because. The EMM Labs costs more than ten times the price of the Benchmark DAC, yet I sometimes prefer the Benchmark's more relaxed yet still very lifelike sound. I have an OPPO BDP-203 Blu-Ray/universal disc player for spinning the occasional 5" silver disc, which is connected to the converter using an Accusound Digital Link cable.



The analog front-end of the review system was built around my reference Basis Audio V turntable, Tri-Planar 6 tonearm, and Top Wing Suzaku "Red Sparrow" phono cartridge. The tonearm's integral cable was connected to a two-chassis Pass Laboratories XP-27 phono stage. I sometimes also used a Pass Labs for the line stage, a two-chassis solid-state XP-22, but more often used a vacuum-tube powered Nagra Classic Preamp in that position.

The speakers used in this review were the Sound Lab Majestic 545 full-range electrostatics. Even though Sound Lab claims their speaker is "full-range," its low-frequency specification cuts off at 35 Hz, and therefore I use a pair of 16" driver SVS SB16-Ultra subwoofers to augment the speaker's lows. The subwoofers claim to have a cut-off at about 16 Hz, below the threshold of human hearing. Their adjustability made them mate well with these electrostatic monoliths. Because the main speakers low-end wasn't completely AWOL, the subs' volume was set relatively low, as was their low cut-off frequency. Yet, as many who use subs along with "full-range" mail speakers, they made a massive difference in the system's overall sound.


Before I installed the D'Agostino S350 Progression power amplifier into the system, my system sounded quite good. Lately, it's been fully dialed in, as I've spent many days and late nights listening to music of all genres from its digital and analog front ends.  I would often jest that my system was my sonic time machine, recreating past events in the recording studio and at live events.

When everything settled in, and I was convinced that the Dan D'Agostino Progression S350 was broken in (even though I didn't hear much difference between when I first powered it up and now), this power amp had sonic abilities that not only surpassed my decent, but one-third the price, Pass Laboratories power amplifier. But the Progression S350 also changed the system's sound into one that was better in every sonic characteristic imaginable.

This isn't the first time I've auditioned a power amplifier that cost more than my reference. As I mentioned above, there are quite a few power amplifiers that cost even more than the D'Agostino Progressive S350. But when it comes to upper-high-end audio components, there have been very few who have the experience of the man Dan D'Agostino. His company before D'Agostino Master Audio was a "small" company called Krell. His reputation precedes him.

The Dan D'Agostino Progressive S350 amplifier's ability to separate sounds from one another in a crowded soundstage was previously unmatched. Plus, with the suitable recording, I could hear a never before realized to this extent a vast, drawn-to-scale soundstage projected behind, between, and outside the boundary of my speakers. The solidity of the center image was extraordinary.



One afternoon while an audiophile friend was visiting, I played the track "Taxman" from a Japanese vinyl pressing of The Beatles Revolver. When hearing George Harrison's double-tracked lead vocal centered between the two speakers, my guest started waving his hands and arms in front of himself like a child seeing a 3-D movie for the first time. The semblance of an actual human being entered my listening room.



I have a very large record collection, yet I don't consider myself a record collector, as I have multiple copies of only a few records. I acquire the best-sounding version and sell the copies of the others I might have. But there are a few records I've acquired multiple copies of because the difference might be subjective, such as Led Zeppelin's II. It was fun comparing the different versions I had when the D'Agostino Progressive S350 was in my system.



I've been asked many times my opinion as to which one I thought was the best version of Led Zeppelin II. Was it the "RL" version from 1969, the one that Atlantic Records founder Ahmet Ertgun rejected because its excess bass made it unplayable on one of his kid's cheap turntables? Or was it one of the early Japanese pressings I had? Or the undeniably impressive Mobile Fidelity Sound Labs version pressed in 1982? Or the one I've always considered the best, the 200-gram pressing on Classic Records from 2000 made with vintage mastering equipment modified to have contemporary specifications? Or is the best-sounding version digital, the 24-bit/96kHz lossless version that can be downloaded on HDTracks that I often stream on Qobuz?



With nearly 900 versions of this album listed on Discogs, I doubt Led Zeppelin fans will ever agree on which is "the best" (although I desperately want to try to get a copy of the 1/4" reel-to-reel tape that was released in 1969, which has the subtitle: The Only Way To Fly). Although it was fun spending an evening sampling all the versions I have, this was mainly because this is such an enjoyable album, "enjoyable" being an understatement, mainly because the signal was passing through the Dan D'Agostino Master Audio Systems Progression S350, which revealed to me so much more detail, so much more of a lifelike sound than I was accustomed to than I've ever had the pleasure of experiencing.

When I say "more detail", I don't mean that I heard it as if the contrast level on a photo was increased, but certain details of the recording process, such as hearing that it was recorded in many different studios and that those involved in making this recording not seem to be concerned with "red line" overdrive that caused distortion in quite a few sections. And, of course, there's more to describe what I heard during Led Zeppelin II's residency on my turntable, so much that I could imagine using all of Enjoy the Music.com's server space with a lengthy discussion of what I heard!



I also must stress that most of the time when listening to this album, I was luxuriating in the sensation of being enveloped by the music on Led Zeppelin II, a recording that I must have heard a thousand times previous to that day. Despite this, before the D'Agostino S350 was in my system, I don't remember ever having the experience of whipping my head around because I thought I heard something entering my listening room from its far corner. Of course, I'd quickly realize this was a tambourine or other percussion instrument entering the perimeter of the huge soundstage.

The frequency extremes the Dan D'Agostino Master Audio Systems S350 reproduced were extraordinary; never before have I heard a treble sound so extended yet so natural sounding. I've had experience with tube amps that had a seductive treble, one that sounded as if it possessed the gestalt of the real thing. Still, the S350 came close to doing this, but at the same time, no amplifier I've previously auditioned gave me the impression that I was hearing as close to what was exactly on the signal feeding it. Transparency is the name of the game, and the D'Agostino Progression S350 sound quality possessed what I would call, without exaggerating, the epitome of transparency.

After the D'Agostino S350 was in my system for a while, I never became accustomed to its supernatural sound. Never before have I had a component in my system that made each musical selections, regardless of how many times I've heard it before, sound as if I've never really heard it. I could use this amplifier to demonstrate every audiophile characteristic that one would desire, frequency extension, transient response, micro and macro dynamics, soundstage, imaging, etc.



As an audio reviewer, I feel as if I should have some negative criticisms, as no audio component is "perfect. I do not want to paint myself into a corner and say this is the best power amplifier on the market. At this level, there are going to be nuances between amplifiers that some audiophiles will prefer over others. And to be honest, I've auditioned nowhere near every solid-state power amplifier on the market. It would be interesting to compare the D'Agostino Progression S350 to an amplifier that costs double or triple its price. But one of those might not match my system as well as the D'Agostino Progression S350. One would be correct if they argued that I liked this amplifier so much only because it was such a good fit with the rest of my system. So be it.

Given that I found absolutely nothing to complain about and lots to love regarding the Progression S350's sound quality, I have no problem recommending this power amplifier to those who can afford it. I'd feel much better if those audiophiles planning to purchase a D'Agostino Master Audio S350 Progression S350 power amplifier also donated money to a cause that can help those less financially fortunate. After I return this power amp to D'Agostino, I will certainly miss it!




Sub-bass (10Hz - 60Hz)

Mid-bass (80Hz - 200Hz)

Midrange (200Hz - 3,000Hz)

High Frequencies (3,000Hz On Up)



Inner Resolution

Soundscape Width Front

Soundscape Width Rear
Soundscape Depth Behind Speakers

Soundscape Extension Into Room


Fit And Finish

Self Noise
Emotionally Engaging

Value For The Money




Type: Type: Solid-state stereo power amplifier
Power: 350 Watts @ 8 Ohm, 700 @ 4 Ohm, and 1400 @ 2 Ohm
Inputs: Two balanced XLR
Signal-To-Noise Ratio: 105dB, unweighted / 75dB A weighted
Total Harmonic Distortion: 350W @ 8 Ohm .015% @ 1 kHz
Input Impedance: 100 kOhm
Output Impedance: 0.1 Ohm
Finish: Silver or Black with custom finishes available upon request
Dimensions: 17.875" x 9" x 23" (WxHxD) 
Weight: 115 lbs.
Price: $27,250




Dan D'Agostino Master Audio Systems
5855 East Surrey Drive
Cave Creek, AZ 85331

Voice: (480) 575-3069
Website: www.DanDAgostino.com














































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