In 2011, Classé Audio introduced the CP-800 preamplifier-DAC ($6500, all prices USD) to replace the well-received, analog-only CP-700 preamplifier ($8000); both models are now discontinued. In 2013 I reviewed the CP-800, our editorial team named it a Reviewers’ Choice, and I made it my reference preamplifier. The CP-800 remained largely unchanged until late 2016, when it, too, was discontinued.
In much the way the CP-800 was a revolutionary leap forward over the CP-700, Classé’s Delta Pre ($9999) leapfrogs the CP-800. The Delta Pre occupies the same aluminum case as the CP-800, measuring 17.5″W x 4.8″H x 17.7″D, but there the similarities mostly end. The Delta Pre is anodized dark gray and weighs 29.7 pounds, or almost six pounds more than the CP-800. Classé’s familiar 16:9 touchscreen remains, granting access to the input and menu selections, but you can no longer change the display color: characters appear only in white on black. I much preferred the CP-800’s blue on white—it’s more modern and engaging. The rest of the Delta Pre’s faceplate is clean, with only three physical controls. There’s a small Power button at far left, and a Menu button to the right of the touchscreen. The latter is tastefully positioned along a black strip that leads the eye to a large, nicely weighted volume knob of black, brushed-aluminum. Also on that black strip, between screen and knob, are: an IR sensor; an asynchronous, charge-enabled 24-bit/96kHz USB input dedicated to Apple portable devices; and a 6.35mm headphone jack.
Near the upper left corner of the rear panel are the Power rocker switch and grounded IEC power inlet. This switch is in its Off position when the side next to the inlet is pressed. Larger power cords, such as my own Clarus Crimson, can too easily be accidentally pressed against the switch during insertion, thereby toggling the switch to Off. Swapping the switch around would solve the problem, but until that happens, those with big power cords will need to be careful.
But that’s my only complaint about the rear panel, which evinces perhaps the most efficient use of space I’ve seen on an audio component. Power rocker and inlet aside, it’s horizontally divided: digital inputs above, analog inputs and outputs below. There are nine digital inputs, from left to right: asynchronous USB-B, Ethernet, AES/EBU (XLR), three coaxial S/PDIF (RCA), and three optical S/PDIF (TosLink). All of these accept signals of resolutions up to 32-bit/192kHz PCM and DSD64; the USB-B also accepts up to 32/384 PCM and DSD256. The digital ins are followed by an RS-232 jack, two Ethernet jacks for use with Classé’s CAN BUS communication system, and IR as well as power trigger ins and outs.
Below these, starting at left, are the analog outputs, in duplicate rhodium-plated balanced (XLR) and unbalanced (RCA) jacks: Sub, Aux 2, Aux 1 (configurable for biamping a pair of speakers or for an additional subwoofer), Main R, and Main L. Then come the analog inputs: two pairs each of balanced (XLR) and unbalanced (RCA) jacks, plus an unbalanced phono input on a pair of rhodium-plated RCA jacks for a high-output moving-magnet (MM) or high- or low-output moving-coil (MC) cartridge.
New in the Delta Pre is an optional HDMI kit ($500), to be installed directly above the digital inputs, which provides four HDMI 2.0b HDCP 2.2 inputs able to process two-channel audio, including DSD64 over PCM, or pass through video from HDMI sources. The kit can be easily installed using a set of screws and some simple wire connectors. The Delta Pre also sports new, custom-made feet from Navcom that are claimed to damp the transmission of vibrations from the surface the Delta Pre sits on.
The Delta Pre can be operated in three ways: with its high-quality, backlit, aluminum remote-control handset; with its front-panel touchscreen and buttons; or with a comprehensive control app compatible with iOS or Android smartphones or tablets. Throughout my listening, the remote worked flawlessly, the touchscreen was intuitive enough in design that I was listening within minutes of completing setup, and the control app offered smooth, instantaneous response from my iPad. The information displayed on the screen varies with the source selected, but common to all sources are volume level, signal type, source, and source mode (Bypass, Pass-Thru, Mono/Stereo). The signal type and input resolution are displayed for digital inputs, and, for the phono input, the gain and load settings. There are also icons indicating the use of the onboard equalization, bass management, Tilt control, headphone input, and turntable. The user can also set and store six different configurations, each enabling a different set of outputs (e.g., RCA or XLR for the Main and Aux channels). This is useful for biamping or sending audio to a second system, activating Bypass mode, or adding one or two subwoofers while tailoring crossover frequency and slope.
In speaking with Dave Nauber, Classé’s brand director, and Sergiu Ignat, the Delta series’ chief designer, I learned that while the Delta Pre is conceptually similar to the CP-800, its circuitry is far more advanced. For example, its six-layer motherboard has been completely redesigned. Ignat proudly pointed out that each layer has been laid out to minimize signal paths and isolate sensitive circuits: layers one and six are dedicated to signal traces, two and five to ground planes, and three and four to power distribution. Power delivery has also been completely reworked by adding a newly designed linear power supply to feed the analog circuitry, and a revised version of the CP-800’s switch-mode power supply to feed the digital circuitry.
The new linear supply feeds power from a toroidal transformer with three secondaries: a simple secondary and two independent split secondaries, one of each of the latter dedicated to feeding power to the input and output circuits. This was done to reduce the risk of ground loops and balance current consumption, which in turn helps dissipate heat more evenly throughout the Delta Pre’s interior. Each split secondary, after rectification, uses four high-quality Mundorf capacitors as principal filters, followed by four more active second-order filters to reduce mains-ripple voltage noise by as much as 60dB. The idea behind all this filtering is to provide the linear low-noise regulators with the smoothest possible voltage, thereby enabling them to deal almost exclusively with load variations. The simple toroidal secondary mentioned above is dedicated to the A/D and D/A converters, each of these equipped with six ultra-low-noise regulators to ensure low output impedance over a wide bandwidth. The slew of other high-quality parts includes low-noise film resistors, film capacitors, and electrolytics from Mundorf and Nichicon. The Delta Pre is specified to produce very low levels of total harmonic distortion (THD) of <0.0005% at 10kHz and intermodulation distortion (IMD) of <0.001%, with a signal/noise ratio of 130dB (22kHz bandwidth, ref. 9V RMS), or 24dB quieter than the CP-800.
As in the CP-800, the Delta Pre’s dual-differential topology uses one DAC per channel, but its implementation has been considerably revised. The DACs are now AKM’s second-from-the-top 4497 chipset, replacing the CP-800’s Wolfson WM8741 chips. Each DAC is equipped with six independent voltage regulators dedicated to either the digital or analog section of the chip or used as a voltage reference. Each DAC is then supported by two ultralow-jitter XTAL master clocks supplied by Crystek: one for sample rates that are multiples of 44.1kHz and one for 48kHz. Each DAC is further supported by a dedicated noise regulator, and jitter is further reduced using a proprietary reclocking circuit.
Activation of any of the Delta Pre’s digital signal processing (DSP) tools—Parametric Equalizer or PEQ, Tilt, the Tone Controls—converts the incoming analog signal to 24/192 using an AKM AK5397 A/D converter. The Delta Pre also includes a new headphone amplifier that combines a defeatable Cross-Feed or X-Feed circuit (Classé uses both names interchangeably) with a high-current buffer stage to easily drive any set of headphones. X-Feed is claimed to produce a more naturally holographic soundfield than the usual “voice in the back of one’s head.” Volume adjustment remains in the analog domain, but is now possible in increments of 0.25dB, via a new, fully differential volume controller based on a higher-quality chipset than was used in the CP-800.
For my money, the upgrade of nearly every internal circuit would have been enough to justify the price increase over the CP-800, but there’s more. Standard kit in every Delta Pre is an entirely new MM/MC phono stage made of significantly higher-caliber parts than those found in the CP-800 and occupying the entire left side of the preamp’s interior. Dave Nauber told me that because this phono stage is fully balanced, the user has the option of connecting a turntable to the Delta Pre using its reconfigurable second pair of balanced XLR inputs, to maintain a balanced signal path from cartridge to loudspeakers. Moreover, the Delta Pre’s touchscreen, remote, or app lets the user change a cartridge’s gain and loading on the fly from the listening chair, instead of having to flip DIP switches or solder pin connections.
Setup
Having owned a Classé CP-800 for a couple of years, I found getting rolling with the Delta Pre quite easy—but its ergonomics are so intuitive that I doubt anyone will have to reach for the manual more than once.
I connected my PS Audio DirectStream DAC with Bridge II, through which I run Roon from a dedicated Intel NUC computer. All analog interconnects tying the Delta Pre to source components and my matching Delta Mono amplifiers or Simaudio Moon Evolution W-7M monoblocks, between which I swapped back and forth, were Kimber Kable KS-1116. All digital interconnects were from Analysis Plus. Speaker cables were Kimber KS-6063, and power was supplied to all components by a Torus AVR 20 power conditioner via Clarus Crimson cords. The speakers were my Paradigm Persona 7Fs.
After swapping out my reference Audio Research Reference 6 preamplifier for the Delta Pre, the first thing I did was enter the Classé’s setup menu to configure XLR1 to what Classé calls Bypass. This turns off all digital signal processing, including the bass management, tone controls, and EQ, to provide a pure analog signal path. (Bypass is not to be confused with Pass-Thru, which is otherwise identical but sets the volume to unity gain.) I was ready to listen.
Analog sound
Using the Delta Pre solely as an analog preamplifier with my PS Audio DirectStream DAC gave me a good handle on the Classé’s fundamental sound. Having recently reviewed Classé’s Delta Monos, which I liked well enough to buy, I was curious to hear if the Delta Pre had a similar sound. It didn’t. The Delta Pre presented aural images more neutrally and literally, and largely absent of the fluidity I found so captivating with the Delta Monos.
In those first listening sessions I partnered the Delta Pre with my Simaudio Moon Evolution W-7M monoblocks. As I listened to “Hey Now,” from London Grammar’s If You Wait (16-bit/44.1kHz FLAC, Ministry of Sound), Hannah Reid’s velvety singing jumped out before me with specificities of image and presence reminiscent of what I’d heard when reviewing McIntosh Laboratory’s C1100 preamplifier. Reid’s voice was chiseled in stone dead center on the soundstage, but about a foot closer to me than I’m used to hearing from my Audio Research Reference 6. Reid’s voice sounded dead neutral tonally, as did Dominic Major’s delicate cymbal taps directly behind her. Dan Rothman’s highly transient electric-guitar notes picked toward right stage were gripping in speed and attack, and I appreciated the depth, tautness, and rhythmic drive of the synth bass forcefully laying down this track’s foundation.
The Delta Pre was transparent enough for me to clearly hear how the Classé and Simaudio amplifiers differ. When I switched to the Delta Monos, the fluid ease and naturalness that I’d so loved while reviewing them immediately reappeared. Despite a hint less micro-level detail being audible from the Delta Monos than from the W-7Ms, the Classés’ greater gravitas throughout the bottom end and heightened sense of realism overall easily made them the more attractive amplifiers to pair with the Delta Pre, so I left them in place for most of my listening.
As I listened to “Trouble’s What You’re In,” from Fink’s Wheels Turn Beneath My Feet (16/44.1 FLAC, Qobuz), a live album compiled from concerts in London, Copenhagen, Lyon, Paris, Prague, Vienna, and Amsterdam, the Delta Pre did a convincing job of communicating the bite, attack, and liveliness of Finian Greenall’s (Fink’s) acoustic guitar. Each pluck of string sounded sharp yet golden, and almost sinewy. The decay of his voice was realistically communicated, and I enjoyed the depth and expansiveness of the audience sound in the background, which lent convincing atmosphere. Nor did the Delta Pre do anything to keep me from hearing the transient of the percussive impact of each of Fink’s knuckle slaps on strings, offering inviting decays resulting from this technique.
Another track I found compelling through the Delta Pre was “I’m On Fire,” from Bruce Springsteen’s Born in the U.S.A. (24/96 FLAC, Columbia); I could feel the punch of Max Weinberg’s kick drum in my feet as it traveled through my floor, and as it thumped me in the chest. Likewise, the weight and body of Garry Tallent’s subtle bass reminded me of what I’d heard through McIntosh’s monstrous MC1.25KW monoblocks when I reviewed them. Tallent’s bass isn’t the most prominent instrument in this mix, but the Delta Pre’s transparency let me hear it clearly.
Digital sound
To evaluate the Delta Pre’s handling of digital signals, I removed the PS Audio DirectStream from the loop and streamed digital files to the Classé from my Intel NUC computer via Apple AirPlay, JRiver Media Center, and Roon. The Delta Pre is an AirPlay endpoint with Roon, and you can also use a USB link.
I began by again streaming “I’m On Fire,” this time wirelessly, in a standard-resolution file (Apple AirPlay doesn’t support 96kHz), and from JRiver via a network using a wired Ethernet connection. This well-recorded track is chock-full of nuances that help me suss out a product’s performance; e.g., Tallent’s subtle bass playing, and the haunting decay of Springsteen’s acoustic guitar. I heard no difference between Apple AirPlay and JRiver; both sounded fine, even a bit lively, communicating most of the information I expect to hear with decent pace, rhythm, and timing.
To evaluate the Delta Pre’s performance when used as a high-resolution streamer and DAC, I closed Apple AirPlay and, via JRiver, played a 24/96 remastering of “I’m On Fire.” I immediately heard an improvement in overall musical texture—the sound was smoother and a bit more open, and microlevel details were a wisp easier to hear than from the standard-resolution file. The 24/96 file also let me better appreciate the kicks from Weinberg’s kick drum, each one more focused, leading to a greater sense of body and impact. Tonally, the hi-rez and standard-rez files sounded almost identical. This exercise demonstrated that the Delta Pre is not only highly versatile, but that its sound was transparent enough to fully communicate the superior sound of hi-rez recordings.
The previous tests also had me wondering how the Delta Pre would stack up against my reference DAC, the PS Audio DirectStream. I shut down JRiver, selected the Delta Pre’s USB input, set up two zones within Roon to enable direct A/B comparisons of the Delta Pre and DirectStream, and tethered the latter to the Delta Pre with a pair of Kimber KS-1116 balanced interconnects. Listening to the 24/96 version of “I’m On Fire” fed from Roon to the Delta Pre via USB, I immediately heard an increase in soundstage size—about 20% in all dimensions—over the same file streamed from JRiver via Ethernet. Springsteen’s voice was also more lively and articulate, a bit more vibrant, and slightly closer to me. Weinberg’s kick drum was communicated with a more familiar character, particularly in terms of authority and definition, and with an inviting delicacy and airiness in the woodblocks and Springsteen’s plucked acoustic guitar.
When I toggled between the Delta Pre’s built-in DAC and the DirectStream DAC connected to an analog input, the differences were more subtle. I heard more texture in Springsteen’s voice through the PS Audio, and while the Delta Pre assuredly didn’t sound dull, the PS Audio put a bit more air between images, sustained the decays of struck woodblocks a bit longer, and communicated the sound of Springsteen’s voice dissipating into nothingness with greater ease. The PS Audio also excelled at articulating the bass notes a bit better.
All of the above was more accentuated with London Grammar’s “Hey Now”: Hannah Reid’s voice was more luminous than through the Delta Pre, while synth-bass notes sounded just a hint more vehement. I also appreciated how electric-guitar notes seemed to float more effortlessly through the DirectStream, and within a vaster soundscape. Overall, in terms of air, body, tonal color, and weight, the PS Audio communicated a sense of rightness or realism that the Delta Pre couldn’t match. However, keep in mind that the DirectStream is a DAC costing $6899 with Bridge II, or almost 70% of the Delta Pre’s price—and the Delta Pre offers much more functionality and many more features.
More digital sound
In addition to its myriad connectivity options, the Classé Delta Pre’s digital section provides several handy ways of fine-tuning the sound in the digital domain. The simplest of these DSP options are the Tone and Tilt controls, both of which involve choosing high- and low-frequency inflection points, and a boost or cut of up to 6dB in .5dB steps. The Tone control offers independent adjustment of bass or treble, while Tilt adjusts the bass and treble simultaneously and in opposition, to shift the tonal balance toward a sound that’s leaner and crisper or warmer and fuller.
I found that Tilt functioned more as a tonal-balance control—as I lifted the treble level, the bass receded, giving the music a slightly cooler, more clinical quality. Tilting the sound the other way seemed to roll off the top end and add oomph to the bottom—almost like listening to a stereotypical tube preamplifier, but without the noise or muddy bass.
In addition to Tone and Tilt, the Delta Pre offers a full suite of bass-management tools: a five-band parametric equalizer (PEQ); adjustment of crossover frequency and slope; single, stereo, or dual-mono subwoofers; and a high-pass filter toggle. In addition, the Delta Pre makes possible the setting of up to six different output configurations for each of its inputs. Such flexibility is a reviewer’s dream—I was able to configure input XLR1 to run in Bypass, which allowed me to evaluate the Delta Pre as an analog preamp. For another configuration I added Tone controls. I then set up a third configuration, to add both of my JL Audio Fathom f112 subwoofers to the system; and a fourth to better integrate the subs with varying crossover slopes. All measurements were taken using a Dayton Audio UMM-6 USB microphone and REW as my analysis tools to properly configure the Delta Pre’s PEQ.
I’m not a big fan of tone controls, but I appreciated how the Delta Pre allowed me to select an inflection point, then apply up to 6dB of boost or cut. In my setup, this helped restore a bit of weight around my room’s 31Hz suckout. I then applied the PEQ’s maximum boost of 3dB. Having exercised enough restraint to ensure that the result didn’t sound artificially boosted, the cumulative effect was a moderately more fulsome-sounding bottom end. What really filled in that suckout was to turn off the Tone controls and add both subs. Adding them with no adjustment of PEQ yielded bloated, uncontrolled bass, and worsened two of my room’s bass modes. But after taking a few measurements, making independent PEQ settings for each subwoofer (using the Aux output to enable stereo subs), and fine-tuning the crossover slope for each sub, I could barely tell that they were on. The only clue was the only one that matters: I heard a smoother, punchier, more linear bottom end, especially below 40Hz. Providing this way of fine-tuning the sound and integrating one or two subwoofers into a system makes the Classé Delta Pre a dream component for listeners who need these features and this kind of flexibility.
Final thoughts
Classé Audio’s Delta Pre is one of the most feature-laden yet ergonomically enjoyable products I’ve reviewed in some time. With analog sources, the Delta Pre sounded communicative, engaging, and well resolved. Used as a preamplifier and DAC, the Delta Pre easily held its own in terms of quality and performance against separate components. But what pushes this two-channel preamplifier-DAC ahead of its competitors are its bass management, PEQ, subwoofer, and source-configuration options. If you’re looking for a central hub for your system that can handle all of your analog and digital sources in one svelte, easy-to-use package, Classé’s Delta Pre is one to check out.
. . . Aron Garrecht
arong@soundstagenetwork.com
Associated Equipment
- Speakers: Paradigm Persona 7F
- Subwoofers: JL Audio Fathom f112 (2)
- Amplifiers: Classé Delta Mono monoblocks (2), Parasound Halo A 51 (five-channel), Simaudio Moon Evolution W-7M monoblocks (2)
- Preamplifiers: Anthem AVM 60, Audio Research Reference 6
- Digital-to-analog converter: PS Audio DirectStream with Bridge II
- Sources: Oppo Digital BDP-103 universal BD player; Intel NUC computer running Windows 10, JRiver Media Center, Qobuz, Roon
- Interconnects: Analysis Plus (USB, S/PDIF), Kimber Kable Select KS-1116 balanced (XLR)
- Speaker cables: Kimber Kable KS-6063
- Power cords: Clarus Crimson
- Power conditioner: Torus AVR 20
Classé Audio Delta Pre Preamplifier-DAC
Price: $9999 USD.
Warranty: Five years parts and labor.
Classé Audio
A Division of Sound United, LLC
380 rue McArthur
Saint-Laurent, Quebec H4T 1X8
Canada
Website: www.classeaudio.com