Reviewers' ChoiceMike Viglas and David Reich founded Classé Audio in 1980. Their first product, the DR-2 class-A power amplifier, quickly gained notoriety for its ability to convincingly drive loudspeakers to unexpectedly high volume levels despite its diminutive power-output specification of 25Wpc. To this day, the success and sound quality of the DR-2 serve as hallmarks for every Classé product since.

In 2002, Classé merged with Bowers & Wilkins. Dave Nauber, who’d previously worked for Madrigal Audio Labs/Mark Levinson, was recruited to assemble the Classé design team and drive the brand forward. David Reich left to join Theta Digital, but Mike Viglas remained as chairman of Classé. Within two years, Classé had launched the Delta line.

Those original Delta models were widely successful, and were Classé’s bread and butter until 2011, when the second generation of Deltas was released, to even greater acclaim. Classé continued to flourish, particularly after introducing their less expensive Sigma series in late 2014, but in 2016 B&W was bought by EVA Automation. Within a year, EVA had put a hold on all new product launches by Classé, including the third generation of Deltas, which had already been silently displayed at that year’s CEDIA Expo. EVA fired all Classé employees other than Nauber, and closed the doors of the Classé headquarters in Montreal. Production and distribution of Classé’s Sigma models continued, but Delta sales were limited to the remaining stock. The future of the Delta line remained unknown. Then, in 2018, Classé was bought by Sound United, parent company of Boston Acoustics, Definitive Technology, Denon, Marantz, Polk Audio, and, as of October 2019, B&W.

Delta: Third generation

Within a year of its acquisition by Sound United, Classé Audio rehired almost all of its former staff, reopened their Montreal HQ, and began production of three new Delta models: the Delta Pre preamplifier ($9999), the Delta Stereo amplifier ($12,999), and the Delta Mono amplifier ($10,999 each). (All prices USD.) Three more Deltas are on the horizon: the Delta Integrated amplifier, the Delta Cinema five-channel power amplifier, and the Delta ISP A/V processor, which will replace Classé’s widely respected Delta SSP-800. Neither specs nor prices for any of these forthcoming products were available when I wrote this.

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Each Classé Delta Mono weighs 97.7 pounds, measures 17.5″W x 8.74″H x 19.37″D, and stands on four newly designed damped feet made by Navcom. Its case looks much the same as those of the second-generation Deltas, but it’s been made marginally more rigid by the increased bracing necessitated by its heavier internal components. Like all Delta models, the Mono is shipped securely supported by molded Styrofoam inserts encased by a thick outer shell of corrugated white Coroplast.

After removing each Delta Mono from its packaging, I placed it on a 1″-thick butcher-block amp stand supported by five spiked feet, and took a moment to appreciate its looks. The single elegantly curved piece of aluminum that forms the front and side panels was instantly recognizable as a Classé Delta, even if it’s anodized a dark gray instead of the light silver of earlier Deltas. The front panel is very clean, with a small, illuminated standby button at far left, and next to it a revised air intake of solid aluminum for Classé’s ICTunnel cooling system (more about this below); on the right is a large window for the all-new, backlit VU meter calibrated to display the amp’s output in decibels and watts into an 8-ohm load. The Delta Stereo shares the same basic design, but with two smaller VU meters, one per channel, occupying a window of the same size, shape, and position.

The bottom and rear panels are all of black-painted aluminum but are finished with different textures. The vented top plate’s brushed finish looks much the same as on earlier Deltas, but the bottom panel, thicker to accommodate the heavier components, has a fine stippled texture. The rear panel has a glass-smooth finish and many connectors. Clustered at top left are Ethernet and USB Type-A ports for software updates, an RJ-45 port assigned to RS-232 control, and another pair of RJ-45s to support Classé’s CAN-Bus system. CAN-Bus is a trick communication feature that enables unilateral control of various functions and settings shared across the Delta line—e.g., VU meter brightness, standby, mute, status information—all of which can be viewed and operated with one of Classé’s touchscreen-equipped preamps or processors. Below the CAN-Bus inputs are two pairs of Trigger inputs/outputs and an Auto Standby toggle. To the right of all these, at the top of the rear panel, are an IEC power receptacle and fuse bay. At the center of the panel are two pairs of rhodium-plated, five-way binding posts made by Furutech, replete with torque-guard technology to prevent overtightening—these are, by far, my favorite binding posts in the biz. Immediately to the right of these are the large grilled exhaust vent and fan of the ICTunnel, and in the upper right corner are high-quality balanced (XLR) and single-ended (RCA) inputs.

202102 classe back detail

After connecting the Delta Monos but before beginning my serious listening, I asked Dave Nauber to walk me through any technical advances that might be under their hoods. He set up a video call with the two of us and Sergiu Ignat, who joined Classé in 2012 and is the technical designer of all new Delta models. It soon became clear that Ignat is passionate about the products he designs, and especially the Delta Mono. We began with the power supply; Nauber mentioned that it “uses a 2.35kVA toroid comprised of 540 meters of copper wire and weighing nearly 37 pounds.” Ignat added that the Delta Mono also has 22 four-pole Mundorf capacitors that contribute a total energy capacity of just over 250,000μF—nearly twice the older CA-M600’s 134,000μF.

Nauber said that part of the reason for the substantial rework of the power supply was that Classé wanted their amplifiers to be able to more easily drive lower-impedance speakers, and in order to do that they needed to move away from the high-power, high-voltage technology used in their second-generation amplifiers and instead go for high current. This involved using the same-size toroidal transformer used in the CA-M600, but lowering the voltage rails to provide more current. This dropped the output into 8 ohms from 600W to 300W, freeing up the desired current, but required significantly more energy storage—hence all those Mundorf capacitors. Nauber then talked about how the Delta Mono and Delta Stereo have lateral MOSFETs, instead of the bipolar transistors used in previous Classé amps. The reason, he said, was that “MOSFETs like to be run in class-A and are more reliable than bipolar transistors. There are four packages on each side of the cooling tunnel, each containing two transistors in a single T0247 package, so in essence, there are 16 transistors on top of the cooling tunnel and 16 on the bottom, for a total of 32 output transistors, if you were to draw an analogy to bipolar devices.”

The total output of the Delta Mono is specified as 35W in class-A, with 300W of class-AB power available into 8 ohms, 600W into 4 ohms, or 1000W into 2 ohms—Nauber assured me that “the Delta Mono will comfortably provide” that full kilowatt. A comparison of the specs of the CA-M600 and Delta Mono shows that the latter trumps the former in other key areas: The Delta Mono has a damping factor of 2000 vs. the CA-M600’s 1500; the frequency response has been widened, from 1Hz–80kHz, +0/–3dB, to 1Hz–650kHz, -3dB; the total harmonic distortion (THD) is considerably lower, at <0.0005% vs. <0.002% (both at 1kHz, balanced); and while the CA-M600’s signal/noise ratio worsened above 2500Hz, the Delta Mono’s remains flat at 120dB well above 20kHz. But for both amps, the gain is the same: 29dB.

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For an amplifier biased this far into class-A, cooling is key—class-A amps run hot. The Delta Mono is kept thermally stable with Classé’s tried-and-true Intelligent Cooling Tunnel, aka ICTunnel. The system works by mounting the MOSFETs directly on the cooling tunnel; a thermostatically controlled fan pulls cool air in through the vents in the front panel, where the air collects heat from the MOSFETs before being exhausted through the rear vent. In use, I could just barely hear the Delta Monos’ fans, but never when more than 4ʹ away. Both amps remained cool and functioned without fault, regardless of volume level—and I appreciated how easy it was to check the individual heatsink temperatures using Classé’s CAN-Bus system.


With the Delta Monos positioned in front of my reference monoblocks, Simaudio’s Moon Evolution W-7Ms, performing direct comparisons was as easy as swapping a few interconnects and speaker cables. Normally, I’d use a pair of Clarus Crimson power cords with power amps I’m reviewing, to ensure cable uniformity throughout my system. But with each Delta Mono Classé provides a very high-quality cord that, Dave Nauber told me, is made by DR Acoustics specifically for the Delta-series amplifiers. Nauber claimed that these cords are similar in quality to an $800-$1000 cord on the retail market, and I have to agree—when I compared the DR Acoustics with my high-current Clarus Crimson cords, I heard no difference.

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I fed signals to the Delta Monos from both my reference preamplifier, Audio Research Corporation’s Reference 6, and Classé’s own Delta Pre (review forthcoming)—a sample of the latter had arrived along with the Delta Monos. The rest of the system comprised a PS Audio DirectStream DAC and a Torus AVR 20 power conditioner. Analog and digital connections were made with Kimber Kable KS-1116 balanced interconnects and Analysis Plus digital links, and Kimber KS-6063 speaker cables connected the Classés to my Paradigm Persona 7F speakers. I streamed music from an outboard USB hard drive to an Intel NUC computer running Windows 10, Qobuz, and Roon.

Brass tacks

I’ve owned pairs of Classé Delta CA-M600 ($14,000/pair) and Delta CA-M300 ($11,000/pair) monoblocks, as well as a CP-800 ($5000)—all three models now discontinued. The Delta Mono costs $7998/pair more than the CA-M600, and twice the price of the CA-M300—I was eager to hear if the juice was worth the squeeze. The Delta Mono replaces both earlier models, despite its power-output specification being closer to the CA-M300’s.

But you’d never know it by listening. The Delta Mono sounded more powerful and brazen, yet more refined, than any second-generation Delta amp I’ve heard. In fact, of all the amps I’ve reviewed, its sound most closely resembled that of McIntosh Laboratory’s MC1.25KW monoblock ($25,000/pair), which is specced to output four times the power. In my room and system, the Delta Monos sounded better, and they cost less. DR-2 influence, check!

In my January 2020 review of the McIntosh MC1.25KW, I said that “only one other amplifier I’ve reviewed has ever instilled in me the confidence that the MC1.25KWs did, and that was Simaudio’s Moon 888 monoblock, at nearly five times the price [$118,888/pair].” Well, now there are two. As long as I kept the Delta Monos’ needles at or under 200W, the limit at which my ears said “No more!,” they sounded every bit as surefooted as the other two juggernauts. True, the Delta Mono can’t deliver the four-digit wattage of the MC1.25KW or Moon 888, but how often do you really need that much power? Where it matters, particularly with perceived headroom, the Delta Monos delivered in a big way.

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When I listened to “Hey Now,” from London Grammar’s If You Wait (16-bit/44.1kHz FLAC, Ministry of Sound), Hannah Reid’s voice soared out into my room, chiseled dead center just above the level of my Persona 7Fs’ midrange drivers. “Hey Now” begins with richly harmonic synth notes flanked by articulately plucked electric guitar. The reverb around Reid’s voice convincingly filled my room—I could hear each echo delicately dissipate. The electric-guitar notes supporting Reid were precisely placed and fast just as they should be, but it wasn’t until about 1:20 into “Hey Now,” when the prodigious bass line pressurized my room, that I went from impressed to gobsmacked. Bass notes were rhythmic, deep, and gripping, chock-full of tactile impact, yet lacked little in terms of resolution—just as they sound through the mighty McIntosh MC1.25KWs. Teasing me to keep increasing the volume, the Delta Monos coaxed from my Persona 7Fs some of the fullest and most controlled bass I’ve heard in my room.

I then played “Born Slippy,” from Underworld’s Everything, Everything (16/44.1 FLAC, JBO). Much as I’d been with the MC1.25KWs, I was taken back to when I heard the band in concert in Toronto over a decade ago—but this time with even more microlevel nuance. Thwacks of the cymbals in the opening seconds exhibited further definition and shimmer without ever sounding splashy, and as the track went on, I could hear more of the audience cheering in the background than I could through the big Macs. The soundstage was similar in size to the MC1.25KWs’, and in accordance with what I’m used to hearing through my reference Simaudio W-7M monoblocks ($25,000/pair, discontinued)—but there was a sense of ease through the Delta Monos that I don’t get with the W-7Ms, particularly at higher volumes. It was this ease that, in part, made the Deltas sound so inviting. Fluidity and warmth are key ingredients of that sound, much as they are of the sound of a very refined yet resolved pair of tube amps—but unlike with so many tube amps, these attributes were never overemphasized by the Delta Monos, and were always balanced with transparency and wall-gripping bass. Moreover, be it high resolution, CD resolution, or lower-resolution streamed music files of electronica, jazz, or rock, this combination of refinement and resolution remained constant, and consistently highly involving.

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I got completely lost in Sarah McLachlan’s piano solo in “Love Come,” from her Laws of Illusion (16/44.1 FLAC, Arista). McLachlan’s voice pierced its way into my room, massive in scale yet wonderfully balanced against her melodic piano playing. I could hear the subtle decay of her voice as it faded into what sounded like a vast background of “black” silence, as well as the sound of her pedaling before keystrokes, and the breaths she takes between sung lines—all almost as if I were in the same room hearing her sing and play.

I found myself hitting the back button a few times while listening to “I’m On Fire,” from Bruce Springsteen’s Born in the U.S.A. (16/44.1 FLAC, Columbia)—it, too, sounded different, and altogether better than I’m used to hearing it through my W-7Ms. First and foremost, Max Weinberg’s kick drum had kick. I could feel it in the floor and in my chest, much as I could through the MC1.25KWs. Springsteen’s voice dripped with body, and Steven Van Zandt’s acoustic guitar was projected with bite. Through my W-7Ms I can hear a hint more textural detail in Springsteen’s voice, and Van Zandt’s strings are ever so slightly more vibrant—but the higher resolution these observations imply come with the loss of a bit of body and solidity, both of which the Classé Delta Monos conjured up in spades. The W-7Ms communicate a better sense of air and space between instruments and voices—but offered the choice between that and the naturalness and more organic sound put out by the Delta Monos, I preferred the latter seven days a week and twice on Sunday.

Measuring up

The Classé Delta Mono balanced the audible advantages of tubed and solid-state amplification better than has any other amp for south of $30,000 that I’ve reviewed. It conveyed all of the qualities of sound I love in the McIntosh MC1.25KW—e.g., the latter’s robust, punchy bass and beautifully fluid midrange—but expertly balanced them with some of what I love about the Simaudio Moon Evolution W-7M: high levels of resolution, transparency, power, focus, and unrelenting drive. And the Delta Mono is cheaper than either.

The Delta Mono fell short in the materials of which its case is made. The McIntosh MC1.25KW, with its thick faceplate of solid glass, huge backlit wattmeter, massive rack handles of solid aluminum, and elaborate case of stamped and polished stainless steel, is one of the most robust-looking amplifiers on the market. Similarly, the Moon Evolution W-7M and all its successors have 1/2″-thick faceplates, huge corner posts machined from billet, 1.5ʺ-thick heatsinks, and beautifully milled and textured top panels—all of solid aluminum. While Classé’s Delta Mono, with its 3/4″-thick wraparound front plate, may look robust, closer examination reveals thicknesses of little more than 1/8″ everywhere else on the case. But while the Delta Mono may not feel as robust or as vault-like as the others mentioned here, as one who’s lived with these amps for over three months now, I urge you not to judge a book by its cover.


Classé Audio’s Delta Mono is stuffed with cutting-edge technology, ultra-high-quality parts, and offers one of the best feature sets in the biz. I loved the new three-stage dimmable wattmeter, and have already exulted about how terrific Furutech’s torque-limiting binding posts are—but it was Classé’s handy CAN-Bus system that made this amp stand out ergonomically.

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Then there’s the sound—it is, in a word, beautiful. Only the combination of Simaudio’s Moon Evolution 888 monoblocks ($118,888/pair) and Tidal’s Piano G2 speakers ($39,900/pair) has sounded better in my room than the Delta Monos driving my Paradigm Persona 7Fs.

Is Classé Audio’s new Delta Mono worthy of a Reviewers’ Choice award? Unequivocally. Is Classé getting my review samples back? Not a chance. Send me the bill, Dave Nauber—I’ve found my new reference monoblock.

. . . Aron Garrecht

Associated Equipment

  • Speakers: Paradigm Persona 7F
  • Subwoofers: JL Audio Fathom f112 (2)
  • Amplifiers: Parasound Halo A 51 (five-channel), Simaudio Moon Evolution W-7M monoblocks (2)
  • Preamplifiers: Anthem AVM 60, Audio Research Reference 6, Classé Audio Delta Pre
  • Digital-to-analog converter: PS Audio DirectStream
  • Sources: Oppo Digital BDP-103 universal BD player; Intel NUC computer running Windows 10, Qobuz, Roon
  • Interconnects: Analysis Plus (USB, S/PDIF), Kimber Kable Select KS-1116 (XLR)
  • Speaker cables: Kimber Kable KS-6063
  • Power cords: Clarus Crimson, Classé stock (made by DR Acoustics)
  • Power conditioner: Torus AVR 20

Classé Audio Delta Mono Amplifiers
Price: $21,998 USD per pair.
Warranty: Five years parts and labor.

Classé Audio
A Division of Sound United, LLC
380 rue McArthur Saint-Laurent
Montreal, Quebec H4T 1X8