Although I do not own a motor yacht or a penthouse loft in a Manhattan skyscraper, I’m more than willing to review a sound system that would fit perfectly in those environments. Classé’s Sigma is just such a system; it’s decidedly high-end, but it’s also capable of fitting into tight spaces.
Typically, I look for maximum performance for the money in any piece of gear I review; aesthetics and physical size tend to be secondary considerations. However, I understand that’s not how the market for luxury goods operates—sometimes you pay a significant premium for great design and craftsmanship. In this case, the retail cost of the review system is $10,000. Let’s see how this slick, compact, and pricey system performs.
For this review, the Sigma SSP ($5000) was paired with a Sigma Amp 5 amplifier ($5000); Classé supplied both units on loan.
The Sigma SSP is a compact 7.1-channel pre/pro with performance specs found in high-end 2-channel rigs. It deftly combines the capabilities of an HDMI-equipped pre/pro and an analog stereo system with balanced circuitry along the entire signal path. The SSP supports AV-friendly features like HDMI switching, multichannel surround processing, and bass management.
For this review, I stuck with a 5.1 speakers configuration (using dual subwoofers) because the Amp5 provides five channels, and I did not want to mix and match amps. A 7.1 system would require the addition of the 2-channel Classé Sigma Amp2 ($3500), twin Sigma Amp Monos ($4000 each), or another Amp5.
The SSP forsakes most of the buttons and dials you typically find on AV pre/pros. Instead, it’s controlled from the front-panel touchscreen, the compact infrared remote, or an iOS app. Home-automation systems such as Crestron and Control4 can operate the SSP through the included RS-232 port.
Speaking of automation and ports, the SSP includes Sigma’s CAN-bus (Controller Area Network) feature, which connects components in a system using Ethernet cables so they can communicate with one another. CAN-bus also allows the SSP to report the system status of any connected Sigma amps and turn those amps on and off. The Amp5 includes a 12V trigger and an RS-232 port on the rear, as well as a CAN-bus input and output.
A large rotary volume control sits on the front of the SSP. It’s not a traditional knob; it rests flush with the faceplate and behaves like a (luxurious) scroll wheel—you operate it with a fingertip. The SSP’s front panel also includes an HDMI input, a USB input, and a 1/4″ headphone jack.
The Sigma SSP’s menu system offers a commendably flexible interface for dialing in various parameters. There is complete freedom in assigning and naming inputs, with the ability to mix and match any audio source with any HDMI video input. One of the more novel features is a video preview; the Sigma SSP can show what’s coming into any HDMI input on its screen. It’s a low-resolution preview, but it lets you know if the source is properly connected to the processor, which can be handy if there’s nothing showing up on a TV screen.
When it comes to video inputs, the Sigma SSP offers eight HDMI 1.4 ports; seven are located on the rear panel and one is on the front. The SSP does not pass UHD/4K video in its current configuration, but its modular main board supports a planned upgrade to HDMI 2.0 with HDCP 2.2 capability. For now, it is a 1080p device. Other input options include three digital-audio coaxial inputs, two digital-audio optical inputs, a USB connection, a pair of balanced XLR analog-audio inputs, and two pairs of stereo analog-audio RCA inputs.
The SSP offers one HDMI output and a digital-audio coaxial output. Analog-audio outputs include a pair of balanced XLR connectors for the front left and right channels, and RCA connections for all 7.1 channels.
A built-in touchscreen and accompanying app let you create and recall custom configurations that precisely cater to your needs. Compared to many AVRs and pre-pros I’ve tried—both mainstream and high-end—Classé’s Sigma is at once simpler and more flexible to program.
The SSP forsakes automated room correction; instead, it offers 9-band parametric EQ for each channel. If you hire a professional installer, or you know your way around REW and own a measurement microphone, you can get excellent results with it. On the other hand, if you expect the SSP to auto-optimize a system using an included mic, as most AVRs and pre/pros do, the functionality is simply not there.
Perhaps one of the most intriguing physical attributes of the SSP is the total absence of ventilation or other provisions for cooling—no fans, no fins, no slots. The smooth-sided chassis is responsible for dissipating whatever heat does build up inside. According to my handy infrared thermometer, the chassis never got above 97 degrees (in a 79-degree room)—cats are going to love it!
The SSP continues to keep it simple when it comes to surround processing. While it does handle multichannel audio, it doesn’t support immersive audio. However, the main board is modular, and the company says it will offer an upgrade to Dolby Atmos, albeit only in the most basic 5.1.2 configuration. In all likelihood, when you are watching a movie in the master stateroom of your mega yacht, you won’t miss those extra overhead channels.
The surround modes it does support include Dolby PLII, PLIIx, and Dolby EX—as well as DTS Neo6. It also handles discrete PCM input at up to 24-bit/192 kHz resolution.
Classé’s Sigma Amp5—which is the same size as the Sigma SSP—offers five channels of 200-watt output into an 8-ohm load, and it has the sort of superior specs that Classé amps are known for. The Amp5 is a class-D design, but the company is quick to note it developed the amp in house and that it offers superior performance versus typical class-D designs.
The Amp5 is equipped with two balanced XLR inputs for use with the SSP’s two balanced XLR outputs. This fully balanced analog circuit path—from the SSP’s analog XLR inputs to the DAC to the Amp5’s amps—is what the company means when it says the Sigma SSP is optimized for stereo sound reproduction. The surround and subwoofer channels use unbalanced connections.
When viewed from the front, the Amp5 looks very similar to the SSP. Each of the Amp5’s five channels supply up to 200 watts into an 8-ohm load—concurrently. Furthermore, with 4-ohm loads, any two channels can provide up to 400 watts concurrently.
Heat dissipation occurs through the amp’s chassis; like the SSP, the Amp5 has no fans or vents. The top of the Amp5 does get slightly warm; it measured 105 degrees Fahrenheit an hour after powering it up and 109 degrees when cranking out tunes and movie soundtracks.
As you saw in the features section, the touchscreen defines the ergonomic experience of the Sigma SSP. Thanks to its clear and logical menu structure, you don’t need an instruction manual to program or use the system—it’s quite intuitive.
Classé’s iOS app worked seamlessly, offering convenient control over volume, sources, configurations, and other parameters; it also shows the current system status. However, it does not directly emulate the SSP’s touchscreen menu. For now, app control is restricted to Apple devices; an Android version is in the works.
The physical remote that came with the Sigma SSP is very small and serves as another example of Classé taking a minimalist approach to design. The company figured Sigma SSP owners would have their own universal-remote solution, or use home automation, iPhones, and/or iPads to run the system.
The remote is made of metal, but it lacks backlighting. Furthermore, there’s no way to tell the few buttons apart by touch. Then again, with so few buttons, it may not matter. You can use the remote to mute the sound, toggle power, change the source, increase or decrease volume, and play/pause/skip music. It also offers one-button access to three configuration presets.
There’s not a whole lot to say about the Amp5’s ergonomics, but it’s all positive. I found the generously proportioned speaker terminals easy to use. I’m a fan of bare-wire connections, and with most amps and AVRs, I find connecting cables to be a bit irritating—but not with the Amp5.
One of the cleverest design touches in the Sigma SSP and Amp5 is how the sides of the chassis flip over to convert them into rack-mount units. It takes mere seconds—there are four screws per unit to deal with—to convert from standalone to rack-mount configuration.
System setup was a lot like what I’ve done in the past using parametric EQ on various devices, such as the miniDSP nanoAVR, Crown XTi amp, or Crestron PSPHD pre/pro I use as a reference.
I installed the SSP and Amp5 combo in my AV studio, and I opted to pair it with GoldenEar’s Triton Five and Triton Seven tower speakers, a SuperCenter XL center speaker, and twin ForceField 5 subwoofers. I’ve grown very familiar with how the GoldenEar Tritons sound, and they were the best speakers I had on hand at the time of this review.
I connected a Samsung BD-H6500 Blu-ray player and a Lenovo Yoga 3 Pro laptop to HDMI inputs 1 and 2; they served as sources for the review. An RCA splitter allowed me to connect the two GoldenEar subwoofers to the single subwoofer output of the SSP. I used 12-gauge Monoprice speaker cables to attach the speakers to the Amp5.
Classé’s no-nonsense approach to audio optimization using parametric EQ is familiar to me, but is a bit technical. While the process can appear intimidating, AVS Forum has a dedicated thread that will walk you through the steps. If you do set up your system this way, you will learn a lot. Alternatively, you can hire a pro to set the system up for you.
The only bit of handholding Classé insists upon when it comes to adjusting EQ is an upper limit of +3 dB when boosting any given frequency. That’s a good thing—every extra 3 dB of boost doubles the required power in the EQ’d range, which can quickly lead to trouble. Also, boosting adds noise, which is never a good idea.
Using Room EQ Wizard, I measured all five speakers as well as the sub, and I created three separate preset configurations using the data. One configuration provided full EQ correction for all channels, another restricted the correction to 300 Hz and below for all speakers, and the third configuration only applied EQ to the subwoofer.
The Sigma SSP is solid, powerful, smooth, and refined. It delivers 1080p video and multichannel audio without a hitch or glitch. Thanks to the Amp5’s ample power reserves, it can keep its composure even when pushed to produce reference-level sound and beyond.
A great example of the smoothness and refinement of the system is how the SSP handles source switching—it applies a brief fade-in, which softens the jarring effect of instantaneously switching between two different audio sources. The SSP even applies the brief fade-in when it’s coming out of mute. In use, I found it as responsive as any pre/pro I’ve used. It’s especially fast at switching between HDMI sources—it took about four seconds. Many Japanese AVRs and pre/pros are clumsy at this task, often taking 5-8 seconds or more to make the switch.
Classé’s specifications indicate the company’s components go toe to toe with other boutique brands’ solid-state offerings, not to mention Classé’s own pricier pre/pros. The vanishingly small amounts of measurable distortion, combined with commendably flat frequency response, produce a pure sound that is neutral and transparent.
Stupendous stereo reproduction is quite possibly the system’s strongest suit. While the exact qualities that result in a bravura performance are often debated, this system had what it took to paint an audible illusion of real space using just two tower speakers—GoldenEar’s Triton Fives. I ran the towers full-range and fed the Sigma SSP lossless 16-bit/44.1 kHz FLAC streams from Tidal, as well as high-resolution files playing through Foobar 2000. I also listened to some iTunes tracks, which sounded great despite the use of 256 kbps AAC compression.
Live jazz is a great test of a 2-channel rig, and the Triton Fives proved a great match for the Amp 5 running full-range. Melody Gardot’s Live from SoHo provided a perfect example of the system’s audiophile bona fides. The power and depth the system achieved swept me away. Melody’s vocals were assuredly a highlight, but the whole performance came through impeccably. If you give the Tritons enough juice to really get going, they manage to sound bigger—and more expensive—than they actually are.
There was no risk of running out of dynamic headroom in my compact 11′ x 19′ x 9′ space. However, I really like deep bass, so I switched on the dual subs and set the crossover for the front speakers to 50 Hz with a 24 dB/octave slope—you can choose between 12 and 24 dB/octave. The result of adding extra low-end authority was simply stunning sound! A new word crept into the vocabulary I planned to use to describe the system: perfection. I couldn’t ask for much more output from any sound system because—frankly—my hearing is too important to me. This is good gear, capable of reproducing the dynamics as well as the nuance of a live performance.
The Triton Fives don’t need subwoofers to play live jazz, but I have plenty of other music that dips down to 20 Hz and below, and I wanted to make sure the subs got a good workout. The soundtrack from Tron: Legacy is a perfect example of an album that pulls no punches when it comes to deep bass, and thanks to the highly linear room response I achieved with parametric EQ, the system rendered the bass perfectly. Low notes were so visceral, it’s fair to say that I both listened and felt my way through the tracks.
To my taste, the audio experience got even better when I switched from stereo to 5.1 surround. On the Sigma SSP, I set the crossover points for all five channels to 60 Hz.
In order to test the system’s prowess when it comes to playing movie soundtracks, I reached for some recent Atmos titles I’m familiar with. One of the cool things about Atmos soundtracks is they still work with non-Atmos gear. I checked out several movies I consider reference-quality in the audio department, including Gravity, Teenage Mutant Ninja Turtles, and Transformers: Age of Extinction. While I do prefer the overall effect of Atmos—I missed the height cues I get from my reference 5.1.4 Atmos rig—the Sigma SSP did an outstanding job at making classic 5.1 surround sound as good as possible.
I never managed to max out the Sigma system, despite my best efforts to be a noisy neighbor. I monitored the power consumption of the Amp5, and even when I blasted the system at deafening levels, it only drew a hundred or so watts from the wall—there’s plenty of headroom left in that box. At normal listening levels, power draw typically stayed under a hundred watts. Furthermore, the Amp5’s external temperature only went up a few degrees while I was cranking tunes; it never exceeded 110 degrees Fahrenheit.
Despite being “only” a 5.1 surround system, the sense of immersion I experienced was a cut above what’s typical. That’s likely because the Triton Fives, Triton Sevens, and the SuperCenter are all extremely good, highly resolving speakers. The qualities I heard during stereo listening were still present—including very precise imaging and crisp dynamics—but the soundfield itself was more enveloping.
One of the most gratifying performances I coaxed out of the Sigma system was using a 4-channel, full-range configuration. No center channel, no subs—just four GoldenEar Tritons and the Classé gear doing its thing. I set the SSP’s EQ to apply full-range correction, and I used Dolby PLII as the upmixer.
Using the four-speaker configuration, I went through all my favorite downtempo and ambient electronic albums from artists such as Com Truise, Bomb the Bass, Boards of Canada, Bassnectar, Air, Brian Eno, and The Orb. The sense of space you can create with synthesized soundfields makes listening to such music in surround a surreal, all-encompassing experience. With all four towers running full-range and the Amp5 in control, the whole room felt energized by the music.
The closer I looked at what the Classé Sigma SSP and Amp5 offer, the more I realized the product is not at all overpriced audiophile bling. Rather, it is a very precise and specific tool; it can provide a maximal experience despite its minimalist design. It performs at a very high level—with the specs to prove it—and it respects people who know what they are doing when it comes to audio calibration.
There are quite a few features in the Sigma system I did not get to touch upon or explore in depth. Presumably, many people who can afford this type of system can also afford to hire someone to set it up in a dedicated acoustically treated room, and to connect it to an appropriately programmed home-automation system.
Currently, the vast majority of movie content out there is 1080p—or less—and comes with a 5.1 soundtrack. The Sigma SSP is very adept at making the most of that combination. Moreover, it treats 2-channel analog audio with the respect it deserves. Crucially, the Sigma SSP is a modular and upgradeable pre/pro with the potential to handle Ultra HD video and Dolby Atmos soundtracks. When combined with the Amp5, this compact but powerful system is a great choice for anyone who is short on space, craves top-notch stereo sound, and can afford Classé’s clever Canadian engineering.
Lenovo Yoga 3 Pro PC (Windows 10)
Tidal HiFi (PC)
Foobar 2000 (PC)
Samsung BD-H6500 Blu-ray Player
Speakers and Subwoofers
GoldenEar Triton Five Towers (front left and right)
GoldenEar Triton Seven Towers (surround left and right)
GoldenEar SuperCenter XL (center channel)
GoldenEar ForceField 5 Subwoofers (two)
KabelDirect Pro Series RCA interconnects
Hosa HMIC003 Pro balanced XLR interconnects
Monoprice 12-gauge speaker cable
BlueRigger High Speed Micro HDMI to HDMI cable (6 Feet)
Mediabridge RCA Y-Adapter (12 Inches)