There is a strong focus on sound quality with the Sigma series but there is also a focus on providing it at a lower price point. The Sigma Series is comprised of the Sigma SSP 7.1 channel surround sound processor, the Amp2 two-channel amplifier and the Amp5 five-channel amplifier. The Sigma SSP is not a feature-laden surround sound processor but it does offer a significant number of options for custom audio setup. Classé has also optimized the Sigma SSP for two-channel music play back. Included is an analog pass through mode along with balanced inputs and outputs for the front left and right channels.
John E. Johnson Jr. reviewed Classé’s flagship surround sound processor, the SSP-800 in 2012 and found the sound quality to be extraordinary. We will see if their lower priced Sigma series proves to be extraordinary as well.
Classé Sigma SSP, Sigma Amp2 and Sigma Amp5
- Clean, sleek looking compact design
- Uncluttered rear panel
- Touch screen controls on the front panel
- Excellent for two-channel and surround sound
- Extensive configuration options for each source
Amp2 & Amp5
- Compact design is easy to handle and situate on an equipment rack
- Substantial power output in a small package
- Detailed and powerful sound
- Styles match the Sigma SSP
Classé Audio has been in existence since 1980 and has produced some exceptional pieces of audio equipment over the last four decades. One of the most memorable amplifiers I have listened to and one that I view as being an iconic piece of home audio equipment is the Classé Omega monoblock amplifier. I only listened to Omega monoblocks one time but they left the impression on me as being the best amplifiers I had ever heard.
CLASSÉ SIGMA PROCESSOR REVIEW SPECIFICATIONS
7.1 Channel Preamp/Processor
Dolby True HD and DTS Master Audio
1.4b HDMI: 7 – Rear Panel Inputs, 1 – Front Panel Input, 1 – Rear Panel Output
Digital Audio Inputs:
3 – Coaxial, 2 – Optical
Analog Audio Inputs:
2 – Stereo RCA, 1 – Stereo XLR
24bit/192kHz for Connection to a PC or MAC
7.1 Channel RCA Output, Stereo XLR Outputs for L/R Front
Can-Bus Connectivity to other Classé Components, Ethernet
Front Panel Touch Screen
Analog Pass-Through Mode (Bypasses all Digital Processing)
3.75”H x 17.00”W x 14.57”D (Excluding Connectors)
10 Hz – 20 kHz, -1dB into 4 Ohms
200W rms into 8 Ohms, 400W rms into 4 Ohms
<0.018% @ 1 kHz Balanced Input
>80 dB below Fundamental into 8 Ohms Balanced
Signal to Noise Ratio:
-100 dB at Peak Output into 8 Ohms (AES17)
3.75”H x 17”.00W x 14.57”D (Excluding Connectors)
10 Hz – 20 kHz, -1 dB into 4 Ohms
200W rms into 8 Ohms – All Channels Driven, 400W rms into 4 Ohms – Two Channels Driven
0.018% @ 1 kHz all Channels Driven
>80 dB below Fundamental into 8 Ohms SE
Signal to Noise Ratio:
-100 dB at Peak Output into 8 Ohms (AES17)
3.75”H x 17.00”W x 14.57”D (Excluding Connectors)
Classé Sigma SSP, Sigma Amp2, Sigma Amp5 Review, Preamplifiers Reviews
Classé has taken a ‘less is more’ approach to the design of the Sigma SSP 7.1 preamp/processor (Pre-Pro). The highest priority in the design is sound quality. They have made no attempted to load it with every type of feature and input/output imaginable. Many surround sound processors have a multitude of costly features and connectivity options that customers might not ever use. There is a ‘wow factor’ that comes from electronics that possess a myriad of bells and whistles but it does not necessarily make them perform any better.
Classé has decided to focus on sound quality and the ability to customize the setup of Sigma SSP. The goal being to provide the best music and movie audio quality at a given price point. The ‘less is more’ approach became evident during my time with the Sigma SSP. Seldom used features are not present. What Classé has done is make the included content the highest quality. My impression of the Sigma SSP is that it would suit a home theater enthusiast who places the highest priority on two-channel audio.
The Sigma SSP does not have an automatic room correction system to tame room resonances. Nor does it possess the ability to pass 4k video or to decode the new immersive audio codecs (Dolby Atmos, DTS:X, and Auro 3D). However, there are plans for upgrades of the audio and video boards.
The Amp2 and Amp5 are the two amplifier options in the Sigma Series. The Amp2 is a two-channel 200w/channel amp and the Amp5 is a five-channel 200w/channel amp. They are both compact in size but are capable of driving difficult speaker loads. They are both class D amplifiers. This allowed Classé the opportunity to package them in a compact chassis.
Classé has decided to focus on sound quality and the ability to customize the setup of Sigma SSP. The goal being to provide the best music and movie audio quality at a given price point.
The front panel of the Sigma SSP is sleek and clean looking. There are only a couple of buttons on the front panel. The display is actually a 4.4” TFT touch screen, allowing the user to make selections on screen. At only 3.75” tall, there is not much room for buttons on the front panel. It is convenient to have access to the menu system but if you are making a significant number of changes, it does seem easier to use a remote. The front panel screen also allows the user to preview the video that is being output from the unit.
The front panel contains a USB input that is capable of playing music from Apple media devices such as an iPod or iPhone. It also has an HDMI input on the front panel making it convenient for temporary connection of a device. The only other distinct feature on the front panel is the volume control, which is flush with the front faceplate, leading to the clean look.
The rear panel is quite clean looking as well. There are seven HDMI inputs on the rear panel of the Sigma SSP. The eight-1.4b HDMI inputs on the Sigma SSP are the only video inputs it has. Many receivers and pre-amp/processors continue to have analog video inputs and outputs. If you are like me, they go unused. When it comes to sound quality, picture quality and ease of installation, the benefits of digital connections are significant. This also simplifies the design of the product. It no longer requires a video processing section capable of upscaling and transcoding video content. If I recall correctly, it has been more than six years since I have used an analog video input on a receiver or processor in my home theater. It did not bother me that Classé decided not to include any type of analog video input. I imagine that more manufacturers will follow suit in the future. The Sigma SSP has one HDMI output and one set of audio outputs. Classé designed it for use in a single zone system.
An interesting feature on the rear panel of the Sigma SSP is a set of connectors for CAN-Bus (controller area network) communication. This allows for communication between the Sigma SSP and other Classé components you may have in your system. The communication is over Cat5 cables and each component has an input and output on the rear panel. The CAN-Bus communication can be used to turn connected Sigma series components on and off as well as display their status on screen. The ability to turn connected components on and off is particularly useful. The Sigma SSP does not have trigger outputs on the rear for turning amplifiers on and off.
There is a USB connection on the rear panel that supports 24bit/192kHz audio formats from a PC or Mac. As well, there is an Ethernet port for connecting to your home network. The Sigma SSP is not wireless though, you will need to connect it to a wireless router or bridge with a Cat5 cable. This allows streaming of audio via Apple’s Airplay or DLNA along with IP control and potential firmware updates.
The Sigma SSP has balanced outputs for the front left and right channels and the remaining outputs are single-ended. This is another example of Classé deciding to focus on quality vs. quantity. I asked about the decision to use balanced outputs for only the front L/R channels and Classé provided a good explanation. They wanted an excellent set of balanced outputs for the front L/R channels for two-channel music listening. To keep the total cost within budget they decided to include an excellent set of single-ended outputs for the remaining channels. This was done instead of including a lesser performing combination of single-ended and balanced outputs for the same cost. This logic is consistent with their focus on sound quality, specifically for music listening.
For analog audio, there is a set of balanced and single-ended inputs on the Sigma SSP. When using the analog inputs there is an analog pass through feature, which allows the user to turn off all digital processing. Classé refers to this as digital bypass mode.
The remote that comes with the Sigma SSP is small and does not have many buttons. The design is quite stylish and it has an expensive feel to it. The back appears to be of machined aluminum and it matches the style of the Sigma products. It is only capable of performing basic operations and it will not control any other devices in your system. I inquired about the design of the remote and the response from Classé is that they feel most customers are going to have specific needs for controlling their system. They feel there is no remote they could package with the Sigma SSP that would satisfy more than a small percentage of customers.
They believe that most customers are going to be using a custom control system or are going to want a remote that is specific to their own needs. I started using the Classé remote but it did not take long for me to switch over to using a Logitech Harmony to control the Sigma SSP. Thankfully I had one sitting around collecting dust. It made using the Sigma SSP much more enjoyable.
For those with iOS devices there is a Classé app available to control the Sigma SSP. As previously mentioned, the Sigma SSP is not wireless. You must physically connect it to your wireless home network through its rear panel Ethernet port. Being that I am an Android user, I did not have a chance to test it out. Classé informed me there are plans to release a control app for Android later this year.
I asked Classé about their plans to offer upgrades to the Sigma SSP since it does not decode Dolby Atmos, Auro 3D or DTS:X and it does not pass 4K video. Classé does plan to offer field upgrades to the audio and video boards in the future. It sounded likely that the upgrade to dual DSP’s to handle Dolby Atmos and DTS:X would happen early next year. There are no plans to support Auro 3D. Since the Sigma SSP is an eight-channel product, it would allow for 5.1.2 audio. Classé plans to offer an update to HDMI 2.0 with HDCP 2.2 once UHD Blu-ray comes to market. Being that UHD Blu-ray will be coming to market near the end of the year, there is not much time left. Pricing for upgrades has not been established.
The Sigma Amp2 and Amp5 are class D amplifiers. Classé based the design off the CA-D200 amplifier from their Delta series. The Amp2 is essentially the same as the CA-D200 but in a Sigma Series chassis. The Amp5 has the same power supply and amplifier circuitry as the Amp2 but modified for a five-channel configuration. The class D topology is what allowed Classé to package the amps in a compact chassis that is only 3.75” tall. The front panels of the Amp2 and Amp5 are identical to the Sigma SSP but lack buttons and a touch screen.
The rear panel of the Amp2 has both balanced and single-ended inputs. It has a CAN-Bus communication input and output for connecting to other Classé components. It surprised me to find trigger inputs and outputs on the back, being that they are not present on the Sigma SSP. The Amp2 also has an IR input and output for connecting an IR receiver and daisy-chaining additional devices. For speaker wire connections, it has two sets of robust-looking five-way binding posts per channel. This makes it easy to bi-wire speakers.
The rear panel of the Amp5 has a similar layout, only modified for five channels. Two of the channels have both balanced inputs and single-ended inputs. The remaining three channels have only single-ended inputs. It has only one set of five-way binding posts per channel. In a 5.1 system, you would have the option of using balanced connections for the front left and right channels. Once again, a feature that supports high-end two-channel sound.
The Amp2 produces 200W rms into 8 ohms and 400W rms into 4 ohms with both channels driven. The Amp5 produces 200W rms into 8 ohms with all channels and 400W rms into 4 ohms with any two channels driven. Due to power supply limitations, it is not capable of 400W rms into 4 ohms with all channels driven. I would not expect there to be many situations in a home theater where this would happen for more than a short period of time.
There are some significant advantages to class D amplifiers but there are also some disadvantages. One of the biggest disadvantages is the dead-band-time when switching between positive and negatives halves. The longer the dead band time, the greater the distortion. It does not take a significant amount of dead-band-time to create significant amounts of distortion. This is the reason that Class D amplifiers have typically been relegated to lower end audio components. Recently, this has started to change as manufacturers are designing solutions to the problems with Class D amplifiers. Classé claims to have reduced the dead-band-time to three nanoseconds with the use of digital signal processing. Since there is little distortion, they claim to be using only a small amount of negative feedback.
The Sigma SSP, Amp2 and Amp5 are all rack mountable. Each side panel can be removed, inverted, rotated and re-installed. This leaves a set of ears to mount the components on a rack.
Setting up the Sigma SSP and getting it connected to my existing components was a relatively easy task. The compact design of it and the Sigma amplifiers make for an easy installation. I always dread having to move my five-channel amp since it weighs about 90lbs. At 23lbs, the Amp5 was a delight to work with.
Being that the rear panel of the Sigma SSP is not jam-packed with inputs and outputs, it is easy to find the connections you need. For sources, I used a satellite receiver, a Samsung over the air HDTV tuner, an OPPO Blu-ray player and a custom-built home theater PC. I connected all the sources to the Sigma SSP with HDMI cables.
During setup of the Sigma SSP, I also proceeded to setup the Sigma Amp2 and Amp5 in my home theater. I connected the Sigma Amp2 to the front left and right channels in my home theater and used the Amp5 for the center and four surround channels. I used the balanced inputs on the Amp2 and the single-ended inputs on the Amp5.
The menu system on the Sigma SSP is straightforward and it is the same whether using the front panel touch screen or the OSD. The configuration of the Sigma SSP can be quite time consuming depending on the level of detail you are after. The basic configuration settings such as labeling inputs, setting crossovers, speaker distances, and speaker levels are an easy task. I only setup one speaker configuration in the Sigma but you do have the option of setting up six different configurations. This is a nice feature if you want to use a different crossover point for your sub for something like two-channel music. Perhaps you might use another configuration if you did not want a sub engaged at all. I am hard pressed to find a use for all six configuration options with my home theater.
The Sigma SSP does not come with an automatic room correction system to tame room resonances. However, it does contain a parametric equalizer that allows for manual correction of acoustic irregularities that may exist in your listening room. Each channel, including the sub has nine bandpass filters that the user can configure based on the response in room. To set it properly, it is necessary to have measurements of noise sweeps taken. This is not something most customers will be able to do themselves and they will require the services of a professional installer. It is quite a powerful tool and a professional installer will be able to attain a superior result. Based on some data previously taken in my room, I did make adjustments at 40Hz and 56 Hz to tame some room resonance. It made a huge difference in reducing the boominess.
I put the Sigma SSP to use in my home theater for all of my usual activities. This includes watching movies on Blu-ray, watching TV on satellite and over the air, listening to two and multi-channel music, and surfing the internet. I found that the sound quality of the Sigma SSP, Amp2, and Amp5 together was excellent no matter what source material I used. This is the first time I have used class D amplifiers and I must say I am impressed at the sound quality of the Amp2 and Amp5. They always seemed to drive my speakers extremely well. The clarity, detail and control were always exceptional. I did not notice any audible distortion regardless of the levels I drove the system to and no matter how loud it got, the Amp2 and Amp5 were barely warm.
Since the Sigma SSP passes through video without any processing, there is not much to discuss on the video side. I was happy with the video quality from all sources I used and never had any issues. Video sources switched flawlessly every time.
Quite often, I will use my HTPC for watching videos on YouTube and listening to music using a service such as Songza. I do not consider this critical listening; it is mostly just for fun. Typically, it happens when I am entertaining people or just wanting to watch some music videos. With content from the HTPC, I do not engage any type of surround processing – everything is in stereo. I decided to play a YouTube video of violinist Lucia Micarelli performing “Aurora-Kashmir”. I had just recently seen her in concert and was quite impressed. The version I watched appears to be an upload from the Josh Groban Awake DVD. The Sigma SSP and Amp2 did a superb job with it given that YouTube’s sound is less than reference quality. I felt the full emotion of her performance on the violin and the soundstage of the band accompanying her was massive.
Tchaikovsky – 1812
Next, I switched over to a high-resolution digital download of Tchaikovsky’s 1812 Overture performed by Eric Kunzel and the Cincinnati Pops Orchestra. I had it stored on the HTPC’s hard drive. Generally, I do not spend much time listening to high-resolution audio downloads in my home theater. I usually use my two-channel system, but I wanted to see how the Sigma SSP and Amp2 would perform. As I mentioned previously, Classé optimized the performance of the Sigma SSP for two-channel music, and with this material it did not disappoint. The detail and clarity were phenomenal. The instruments in the orchestra sounded alive. I felt like the playback of this recording on the Sigma components was the best I have ever heard it.
Chris Botti in Boston
To see how the Sigma setup would do with some higher quality surround music on Blu-ray, I put Chris Botti in Boston on. I selected the Dolby True HD 7.1 soundtrack for my listening tests. There are many great performances on this disc and I find that I enjoy them no matter how many times I watch them. There are a number of songs that showcase Chris Botti’s talent on the trumpet but a couple that I particularly enjoy are “Hallelujah” and “Cinema Paradiso”. With the Sigma SSP and amplifiers, his trumpet sounded the same as it does live. In “Cinema Paradiso”, he accompanies Yo-Yo Ma and they perform fabulously together. Once again, the Sigma setup had perfect clarity. The violin and cello sounded detailed and rich. The Sigma Amp2 and Amp5 drove my speakers in what seemed like an effortless manner during all the songs I listened to, many at reference levels.
I watched a few different movies on Blu-ray during my time with the Sigma SSP and amplifiers. The first movie I watched was Fury, the story of a U.S. tank crew doing battle in Germany during the final days of World War II. I selected the DTS 5.1 Master Audio soundtrack and engaged PLIIx processing in the Sigma SSP for the rear surrounds. The battle scenes in Fury contain extremely powerful audio and the Sigma amplifiers did an outstanding job at driving my speakers. The sound effects were fast and had punch. There is a significant amount of low frequency sound during some of the scenes and the Sigma SSP impressed me with its control. I only performed a small amount of adjustment using the parametric equalizer when I set up the Sigma SSP to reduce room resonances. It seemed to work quite well, as I did not notice a significant amount of resonance or booming that would otherwise exist. With some additional effort into setting the parametric equalizer, I feel like it would rival some of the best automated room correction systems.
Other movies on Blu-ray that I watched in my time with the Sigma Series equipment were American Sniper and Unbroken. American Sniper is the true story of Navy Seal sniper Chris Kyle, who serves in Iraq providing sniper coverage for ground troops and envoys. Both the audio and video on American Sniper are stunning. The soundtrack is a Dolby True HD 7.1 mix and the Sigma SSP and amplifiers handled the audio perfectly. The sound was impactful and the Amp2 and Amp5 handle the dynamics of the battle scenes extremely well.
Similarly, the audio and video on Unbroken are exceptional. Unbroken is the story of Louis Zamperini – a World War II bombardier who becomes a P.O.W. after his plane crashes in the South Pacific. The audio is a Dolby 7.1 True HD mix that is immersive and feels very realistic. Once again, the Sigma SSP and amplifiers handled the audio perfectly. The sounds of airplanes and gunfire were powerful and detailed.
THE CLASSÉ SIGMA has Amazing Sound Clarity and Produces Huge Amounts of Power.
- Classé optimized the Sigma components for two-channel music playback. The sound quality is extremely good with any material but two-channel playback stands out.
- The Sigma SSP and Sigma amplifiers are compact in size and easy to handle. They produce a significant amount of power for their compact size.
- They have a sleek looking design that is free of clutter.
- There is a touch screen on the front panel of the Sigma SSP, allowing access to the setup menu.
- There are extensive audio setup options on the Sigma SSP for each source.
Would Like to See
- The Sigma SSP is not capable of decoding the new immersive audio codecs such as Dolby Atmos or DTS:X. Nor is it capable of passing 4K/UHD video. However, Classé will be offering upgrades.
- The remote control included with the Sigma SSP does not have many functions. It is not a universal remote capable of controlling other devices.
- An automatic room correction system is not included. Audio setup of the Sigma SSP will be difficult for many owners and the services of a professional installer will be required.
The Sigma SSP, Amp2 and Amp5 setup performed superbly during the time I had them. The audio quality was first-rate whether used for music or movies. When used for two-channel music, the Sigma SSP and Amp2 sounded detailed and clear. For multi-channel music and movies, the sound was immersive and impactful. If two-channel audio is a high priority in a surround sound processor then this may be the setup for you.
A key factor in enjoying the Sigma SSP is having it installed and setup properly from the start. Owners need to pay close attention when choosing a remote or a control system, setting the speaker configurations and adjusting the parametric equalizer to tame room resonances. I can see this being a daunting task for inexperienced owners and the services of a professional installer will be required. Even for an experienced home theater enthusiast, it might difficult to get the parametric equalizer set properly to produce the best sound possible. This is of course a factor in the purchasing decision. The good news is that Classé products are typically sold by dealers that offer these types of services. Having dealer support will also make the future installation of upgraded audio and video boards convenient for the owner.
I would encourage any home theater enthusiast who is interested in high quality two-channel audio and the ability to customize to give the Sigma SSP, Amp2 and Amp5 an audition.