Classé Audio Delta Pre Preamplifier/Processor and Delta Stereo Amplifier
What do we really want from our electronics, those (usually) necessary boxes between our audio sources and loudspeakers? Of course we need control—which source do we listen to, how loud, etc.—and we want these components to be easy to use and dependable. But, mostly, we want them to disappear. Unlike upgrading a phono cartridge, D-to-A converter, or speaker from which we expect more—more bass, more dynamic range, more dimensionality—with electronics, in the final analysis, we want less. It was with this undeniably difficult-to-define standard in mind that I got to know Classé Audio’s Delta Pre preamplifier/processor and Delta Stereo power amplifier.
The Montreal-based company introduced the third iteration of its Delta series components at High-End Munich in 2019. In addition to the two products considered here, a new single-channel amplifier, the Delta Mono ($10,999 each) also debuted. A five-channel power amp is coming next and there are plans, as well, for a surround processor and integrated stereo amplifier. This considered course of developing products and introducing them to the marketplace is expected from a company like Classé, well regarded by both recording professionals and discerning hobbyists. But, in fact, the brand has been on something of a roller coaster ride in recent years.
David Reich, an amplifier designer, and Mike Viglas, an audiophile who had the means to invest in the enterprise and who eventually became its sole owner, founded Classé Audio in 1980. (Viglas became wealthy as a hugely successful Ford heavy truck dealer. Dave Nauber, an audio industry lifer with Classé for 18 years and now the Brand Director, loves recycling an old joke when he tells the story of the company’s beginnings: “How do you make a small fortune in the audio business? Start with a big one.”) Nearing retirement age, Viglas instituted a distribution agreement with Bowers & Wilkins in 2001 and sold Classé to the venerable British speaker manufacturer in 2010. Then in 2016, rather unexpectedly, B&W was purchased by a Silicon Valley start-up, Eva Automation, which was looking for an established product in which to implement its cutting-edge wireless technology. “It’s arguable that, when they bought B&W, they didn’t even know they’d bought Classé,” recalled Nauber, sounding a little hurt. It was clear that Eva’s plans “had nothing to do with Classé” and operations in Montreal were shut down the following year.
Fortunately, salvation came in 2018 when Sound United acquired Classé, adding it to a roster of successful audio manufacturers that includes Denon, Marantz, Definitive Technology, Boston Acoustics, Polk, and HEOS. Nauber is in charge of the brand and the design team remains in Québec. The products are built at Sound United’s state-of-the-art Shirakawa Audio Works factory in northern Japan.
This history informs some of the design features of the latest Delta components, especially the amplifiers. Both the monoblock and the stereo models had to be unflinchingly powerful because they were developed with B&W loudspeakers in mind. “If you look at the impedance of a B&W 800 or 802,” Nauber told me, “you’ll see that between 70Hz and 1000Hz it’s below 4 ohms. That was one of the elements that figured into our design goals. We wanted an amplifier that could drive a lower impedance load and do so effortlessly yet still have enough power at 8 ohms. Essentially, whatever you connect to it, you’ve got plenty of power.” The Delta Stereo ($12,999) is a brute, weighing in at 102.3 pounds, though it registers as surprisingly compact on casual inspection; it’s just not as formidable-looking as your typical 250-watt (into 8 ohms) stereo power amplifier. The latest Delta components maintain the distinctive chassis “wrap” of earlier models—a single piece of 3.18mm-thick extruded aluminum begins at one back corner and sweeps around the front to the other back corner. The first 12.5 watts of those 250 are Class A, so there’s got to be some serious heat generated, right? Where are the massive heat sinks? How do these things breathe? The answer is that Classé amplifiers continue to employ an active cooling mechanism. There’s an utterly silent thermostatically-activated fan inside, with blades thicker than those in the previous Delta generation. It scoops more air in with each revolution and thus doesn’t need to go faster to dissipate more heat. Air from the environment enters the Delta Stereo through a louvered intake vent on the front panel and moves though the “Intelligent Cool Tunnel” to exit through the rear of the enclosure. Even with the amplifier on for several days and playing demanding material, the top of the chassis doesn’t get warm to the touch, though the rear exhaust port certainly does. The cooling system allows for Classé amplifiers to be stacked vertically, so long as there’s adequate ventilation behind them. It’s a reason why Classé amps have been popular with recording studios (London’s Abbey Road, for instance) and movie theaters, as well as with audiophiles who can confidently situate them in an equipment rack or cabinet without fear of overheating. The designers were keen to control internal temperatures for the usual reasons: The amps’ carefully chosen parts will perform as intended and last longer.
A good portion of the aforementioned 102.3 pounds is accounted for by a hefty toroidal transformer, hand-wound with roughly a third of a mile of copper wire, with separate secondary windings for each channel. A total of 22 top-grade Mundorf capacitors assure ample energy-storage capacity. The circuit boards for the Delta Stereo’s right and left channels are exactly the same, unlike many other high-end stereo amplifiers that boast separate boards for each channel but actually employ mirror image circuits, with signal paths that are not truly identical. The new output stage employs lateral MOSFETs, less efficient than their vertical brethren, but more linear in their behavior. The front panel sports a pair of elegant VU meters, which some may see as merely decorative—they can be turned off if the bouncing needle gets on your nerves. Nauber says, “It’s kind of like having a candle on the dinner table. You don’t need the candle for light but it adds a certain ambiance. From the standpoint of sales training, we talk about the meter because it helps people understand where the Class A operating range is. With most of the listening you do, the amplifier will be in Class A.”
On the rear panel of the Delta Stereo are two sets of rhodium-plated-copper 5-way binding posts and both RCA and XLR inputs. There are connections to support an IR remote control, DC trigger inputs/outputs, and a port that allows for network connections. Additional connectivity includes a USB port for updating firmware, an Ethernet port, and an RS-232 control port. The amplifier is supplied with a very substantial detachable power cord, designed specifically for the Delta Stereo by DR Acoustics. It’s claimed to be immune to temperature increases than can impede the flow of current. To aid in controlling unwanted vibration—the shape of the chassis also plays a role—both the amplifier and the Delta Pre sit on Navcom footers that are tuned to the weight of the component. As it’s considerably heavier, the amplifier has much stiffer feet than the preamplifier.
The front panel of the Delta Pre ($9999) is remarkably spare, given the ambitious functionality of the unit. There’s a power button that takes the device from standby to active status, a large rotary volume knob, a headphone jack, and a USB input that facilitates the use of Apple portable media devices. Mostly, though, the center of attention is a 3½” x 2″ touchscreen used for operating the preamp, setup, and display. A nearby Menu button changes the Home screen to the main page of the Menu, and you’re off to the races. Classé was the first audio manufacturer to use a touchscreen, three years before the original iPhone revolutionized the mobile device world. Dave Nauber observed that although the touchscreen utilized in Classé Audio products was expensive to develop, it ultimately saved money, as every control product can employ the same screen. It’s the software that varies from device to device. “It allows us to reuse a piece of engineering over and over without having to reinvent the wheel.”
A blow-by-blow account of all the preamp’s operational capabilities would be both pointless and tedious but, as you’d anticipate, one can readily access inputs, label and configure them (say, set input offset or pick a cartridge loading value), and address network requirements. When it’s not being programmed or used to make Menu choices, the touchscreen serves as a display that indicates the gain setting in large numbers easily read across a dark room as well as in broad daylight. Other information, such as the source playing and file format, is shown in smaller characters. The hefty aluminum remote control can do everything the touchscreen does, though programming/setup is more readily accomplished by utilizing the screen. The remote does have eight “Function” keys that can be programmed to serve as shortcuts to favorite commands.
The analog-domain stepped attenuator features an exceptionally large number of steps, allowing for very precise volume setting. Adjustments can be made in increments of just 0.25dB from -93dB to the 0dB reference point and in 0.5dB advances for 14dB above it. That’s 400 steps. The ability to set the turn-on level for each source is a big plus, as you’d be spinning the volume knob (or pressing the equivalent button on the remote) forever, if you had to start from -93dB. The factory default is -30dB.
The Delta Pre’s rear panel reflects the unit’s robust connectivity. Digital audio inputs include USB (PCM up to 32-bit/384kHz and DSD up to 256), AES/EBU (PCM up to 32/192), and three (each) coaxial and optical connections (both PCM up to 32/192). The USB input does support native DSD—the Delta Pre utilizes a pair of AKM 4497 DAC chips, implemented in dual-differential mode—but this necessitates downloading and installing a Windows Thesycon/Classé USB driver into your server. Without the driver, you’ll get DoP—not exactly the end of the world. For analog sources, Classé provides two sets of balanced inputs and two sets of RCAs, in addition to a pair of RCA connectors specifically for phono. Classé provides a total of five outputs, all with balanced and single-ended options. There are outputs for the main left and right channel and a subwoofer; the other two outputs (Aux 1 and Aux 2) can be configured to mirror the main stereo channels for bi-amping, or one can send signal to a second sub.
There’s also an input for an IR repeater, just in case the remote can’t “see” the Delta Pre reliably (say, because it’s in a cabinet), an Ethernet connection, the main power on/off switch, and an IEC outlet for the supplied power cord, a much more modest one than the ophidian number supplied with the Delta Stereo. Owners can choose to order the preamp with an HDMI input for an extra $500. Dave Nauber estimates that 20% of Delta Pre customers get the HDMI interface, which means that the other 80% are saving $500.
When setting up the preamp for each source, the user indicates if Digital Bypass should be employed. If it is, the volume control is active but DSP features aren’t. With Digital Bypass off, an analog signal is converted to PCM and functions such as bass management can be engaged. Speaking of which, a bass-management menu appears if a subwoofer has been detected for a given source. The crossover frequency between the main speakers and sub can be specified, as well as the crossover slope. In the Phono set-up menu (selecting that input automatically bypasses digital processing) the user indicates if the cartridge-du-jour is a moving magnet, low-output moving coil, or high-out moving coil. An impedance loading option is then selected—50-450pF in nine 50pF steps for mm, eight choices for low-output mc, ranging from 7.5 to 1000 ohms, and one choice only for high-output mc, 47k ohms.
Unlike some other sophisticated preamp/processors, Classé’s Delta Pre doesn’t offer automated DSP room correction. Dave Nauber has some fairly negative views on this technology, feeling that the algorithms over-promise and under-deliver—a viewpoint that, obviously, many satisfied users of Dirac, Audyssey, Anthem, Lyngdorf, and several other software packages would take issue with. “These systems are all based on assumptions about average rooms or reflective surfaces,” Nauber maintains. “They’re approximations of what should be done. They will rarely get the exact same result twice—each time you do the measurements and then see how the filters are actually set, the automated system will choose different values.”
What the Delta Pre does have are advanced parametric equalization capabilities that permit “very precise digital audio filters to help compensate for fixed sonic irregularities defined by the location and characteristics of your speakers, your room, and your listening position in the room,” to cite the owner’s manual. For each loudspeaker, including the subwoofer(s), as many as five filters can be implemented with the user picking the center frequencies of each band and then adjusting the level and Q. Powerful stuff. But there can be no doubt that Classé means to discourage consumers from attempting EQ calibrations on their own, the manual urging them to have measurements and adjustments made by “a well-qualified acoustical engineer.” Dave Nauber guesses that roughly half the Delta Pre customers don’t use EQ at all and, of the half that do, 20% bring in a pro, 30% ask the dealer to have a go at it, and 50% actually do it themselves. It’s not just the capacity to make room measurements, Nauber maintains. “You need human judgment. Some anomalies need to be fixed and others don’t.”
Mostly, I listened to the Delta components as a pair, though I did try using the Pre with alternative amplification and the Stereo with a different DAC. Two pairs of loudspeakers saw service, Sonus faber Olympica Nova IIIs (bi-wired with T+A Speaker Hex cables) and Magico S1 Mk2s (connected to the amplifier with a single pair of Transparent Gen 5 Ultra speaker cables). The interconnects between the Delta Pre and the amplifier were a 15-foot run of balanced Transparent Gen 5 Ultra. Digital sources included Baetis Reference and MusiCHI SRV-1 servers; an Oppo BDP-103 was used as a transport. The analog front end was a VPI Scoutmaster equipped with a JMW Memorial tonearm and the high-output version of Sumiko’s Blue Point Special EVO III cartridge.
I used the Classé Delta components as my primary control and amplification electronics for a month, the amp intermittently for several weeks longer. When the preamplifier was first installed, the sound of my system became soft-edged and billowy—“polite” in a way that wasn’t terribly involving. This phase was short-lived, no more than 20–30 hours, and from then on the Delta Pre and Stereo were a pleasure to operate and, more importantly, to listen to.
There are two Pre functions not mentioned above that could be of at least occasional utility to some users. The first is Apple AirPlay: The preamp can readily deliver content from an iOS device that’s connected to the same network. When you choose the Delta Pre from your phone/tablet/computer’s list of network devices, the preamplifier automatically switches to Network as the source and you’re good to go. What could be more ideal for a get-together of audiophiles? The group could take turns playing their reference material through the host’s system with a minimum of fuss.
The second feature involves the Delta Pre’s tone controls—two words that are anathema to some audiophiles. These can be used in the usual fashion to provide a boost or cut of as much as 6dB to frequencies below or above values chosen by the user. Of special interest, though, is the Pre’s “Tilt Control” option. This adjusts frequencies above and below user-specified inflection points—the default settings are 200Hz and 2000Hz—so that a dull-sounding recording can “tilt” towards a more lively tonal balance and an overly bright one can be tamed. I have a 24/96 file of Linda Ronstadt’s Greatest Hits that is difficult for me to listen to, as much as I like the music. The singer’s voice is harsh and peaky, guitars are tinny, strings sound wiry, and drums are dimensionless. Applying 2dB of downward “tilt” raised the low frequencies and attenuated the highs to make this particular mastering listenable. More than listenable, actually—enjoyable.
Back to flat tone settings and sources that don’t fit in a pocket. I listened to dozens of familiar recordings to determine if their fundamental character came through unadulterated. From the standpoint of tonality, the Delta components together were neutral, not editorializing in the least. Singers had their voices reproduced in a way I understood as “correct” from years of hearing these recordings through many good audio systems, and, in some instances, the occasional live concert. All of them sounded like themselves. The same could be said for instrumental voices, say the unique timbres of great tenor sax players—Dexter Gordon vs. Lester Young, Joe Henderson vs. Sonny Rollins. Accuracy in the midband usually gets the credit for this kind of neutrality, but getting the overtone structure right all the way up is also crucial, and it’s apparent that the Delta gear does this well.
What’s interesting to me is that I thought of my reference XA 60.8 Pass amps as quite neutral, and I still do. It’s apparent, though, that there can be different versions of “neutral.” The Classé’s’ presentation is forward and vivid without egregious distortion of the engineer’s intent. This was more evident with the Magico speakers than the Sonus fabers. Both amps make music utterly engaging, but it comes down to personal preference, as it usually does. When I compared the Delta Pre to my day-in/day-out DAC, the T+A DAC 8 DSD, which has a volume control that allows direct connection to the amplifiers, there were differences, but they seemed less important. Bass was slightly more focused through the T+A; drum sound was punchier with the Classé in the path. I couldn’t hear any musically meaningful differences in tonality or spatial parameters. That’s saying something, given how smitten I’ve been with the T+A DAC over the past couple of years.
The ability to adjust the gain in such small increments with the Pre is a strong selling point. For classical music in particular, there’s a correct playback level determined by the recorded perspective. Playing a recording with a mid-hall perspective too loudly in an effort to force an immediacy that isn’t there is a mistake; setting the volume too low for a recording made with the conductor’s aural viewpoint is likewise a recipe for failure. How many times has the “correct” gain setting been between two clicks on a stepped attenuator? That’s unlikely to happen with the Delta Pre.
Although, admittedly, neither of the loudspeakers used to evaluate the Classé components was an especially challenging load, there was nonetheless a sense of ample dynamic headroom. The orchestral climax halfway through the opening movement of Bernard Haitink’s Concertgebouw recording of the Shostakovich Symphony No. 15 crested gracefully, better than I expected with the modest two-way Magico S1 Mk2s sans subwoofer, played at a healthy volume. Same thing with well-recorded drums—the snare on “Ghetto of My Mind” from Rickie Lee Jones’s Flying Cowboy CD had the “sock” you’d associate with bigger speakers playing full out. Spatially, the Delta Stereo performed as well as any other two-channel solid-state amplifier I’ve heard with symphonic recordings that excel with this parameter—the Haitink Shostakovich performance, for example. The representation of the musicians as they sat on stage and the air of the great Dutch hall were not as effectively reproduced as when my usual XA 60.8 Pass monoblocks drove the Magicos. All things being equal, or close to equal, it’s probably a fact of life that mono amps will always surpass a stereo model when it comes to soundstaging and imaging. If this particular audio metric is of prime importance, you should perhaps consider a pair of the Delta MONOs, assuming you have the space (and the additional nine large) to go that route.
The Pre phonostage was very quiet, even though it was necessary to turn up the gain a good deal to achieve satisfactory volume levels with orchestral recordings. All of vinyl’s glories were evident. With my prized copy of the M+K direct-to-disc For Duke, the sound was tangible. Especially for those who listen only occasionally to LPs, the Pre provides all the phono- stage you’ll ever need.
Regarding my earlier concerns that the Pre’s parametric EQ might be underutilized by a sizable percentage of owners: I should say that I didn’t feel a powerful need for any adjustments myself. I do use DSP room correction (Anthem’s ARC) for surround listening but don’t find a compelling need for it with stereo. Dave Nauber commented, inscrutably, that Classé’s imminent surround processor “may or may not contain some sort of automated system. If it does, it’s likely to be because we caved.”
Classé’s Delta Pre and Stereo are impeccably designed and manufactured products that offer impressive operational flexibility and dependability. The amplifier provides enough power to handle just about any loudspeaker you’d care to send its way. These two components are visually appealing and practical to install in a domestic setting. And they “sound good,” meaning that they get out of the way and let the fundamental character of a recording be determined by the engineers involved. The Delta Pre and Stereo have nothing to say on the matter, and that’s exactly as it should be.
Specs & Pricing
Delta PRE Preamplifier
Type: Two-channel solid-state preamplifier with DAC and phonostage
Analog inputs: Two balanced, three RCA, (one designated as phono)
Digital inputs: Coaxial (3), optical (3), AES/EBU, USB, HDMI optional
Phono inputs: Two supported (one XLR, one RCA) configurable for moving magnet, low-output moving coil, and high-output moving coil
Formats supported: USB input: 32-bit/384kHz PCM and DSD2.2/5.6/11.3MHz, coaxial, optical, and AES/EBU inputs up to 32-bit/192kHz PCM
Outputs: Balanced and RCA right and left, subwoofer, two aux (one can be assigned to a second sub)
Dimensions: 17.5″ x 4.75″ x 17.5″
Weight: 29.8 lbs.
Delta STEREO Amplifier
Type: Solid-state Class AB stereo amplifier (Class A to 12.5W/8 ohms)
Output power: 250W into 8 ohms, 500W into 4 ohms
Inputs: One pair XLR, one pair RCA
Input impedance: 82k ohms (balanced and RCA)
Outputs: Two pairs of 5-way binding posts
Dimensions: 17.50″ x 8.74″ x 19.37″
Weight: 102.3 lbs.
380, rue McArthur
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