068

CLASSÉ SIGMA SSP,

AMP2 & AMP5

PROCESSOR/PREAMP &POWER AMPLIFIERS

Reviewer Stephen Dawson

When it comes to high-

end analogue stereo

equipment, times for the

discerning audiophile

have never been better.

But what to do if you are

both audiophile and a lover of movies and their

multichannel soundtracks? Or if you believe that

each channel of the glorious modern surround

sound music discs deserves the same exemplary

treatment as stereo discs?

Canadian fi rm Classé Audio has long been

producing products for such enthusiasts. The

company’s focus has been on quality sound since

its beginnings in 1980. Now to its highly regarded

range of stereo and surround pre and power

amplifi ers, it has added the relatively aff ordable

Sigma range. We had the opportunity recently

to spend a few weeks with Classé’s Sigma SSP,

AMP5 and AMP2.

SURROUND PROCESSING

Combined — and speaking only conceptually

here — these three units function as a high-end

7.1-channel home theatre amplifi er. But that would

be an amplifi er of a kind rarely if ever seen, given

the focus here on audiophile quality from the

point a signal enters the SSP through to the time it

reaches the hefty speaker output terminals.

The Sigma SSP is the surround sound processor

and pre-amplifi er. Although a great deal of design

attention has been given to the purity of analogue

signals, it is in fact mostly concerned with digital

inputs. There are only three analogue inputs, all

at line level (no turntable friendliness), two of

them standard RCA connections, and the fi nal pair

balanced XLR for the cleanest possible signal from

suitably equipped source devices.

The SSP features plenty of digital inputs: two

optical, three coaxial, eight HDMI, one USB on the

front panel for iPods and so on, one USB-B on the rear

which allows the unit to act as a USB audio device,

and one Ethernet on the rear for AirPlay and DLNA

streaming. PCM digital audio up to 24 bits and 192kHz

is supported, though not Direct Stream Digital.

Classé notes that the circuitry within the unit

is derived from its considerably more expensive

CP-800 preamplifi er. For a straight analogue path the

unit is specifi ed with a frequency response of 8Hz to

200,000Hz within a 1dB envelope, and an unweighted

signal-to-noise ratio of 104dB.

On the video side, the HDMI inputs pass through

signals up to 1080p in 3D, but don’t seem to handle 4K.

It does not process the video signal in any way other

than to overlay an on-screen information panel when

you’re adjusting the volume, input or other setting.

There are outputs for up to 7.1-channels, with the

front left and right available either as RCA or balanced

XLR. (If you’re using a Classé power amp you will, of

course, be using XLRs for the two main channels.) The

centre, surround and subwoofer channels are fi xed in

purpose, but the fi nal two are multipurpose. They can

be set to surround rear (for regular 7.1-channel sound

and Dolby Pro Logic IIx), front height (for Dolby Pro

Logic IIz), bi-amping to provide double the power to

the front stereo speakers, or two-channel downmixing

of the entire signal. This allows a stereo in another

room to carry the entire signal.

The SSP is compatible with multichannel PCM

and all the Dolby and DTS standards including their

high resolution lossless forms up to 7.1 channels. And

as is the norm with such processors, it can also process

two-channel into multichannel sound, including the

aforementioned Dolby Pro Logic IIx and IIz and their

DTS equivalents. One nice feature: there’s also a mono

mode. If you’re watching an old movie or listening to

an old recording, mono mode mixes the entire signal

to the centre channel speaker rather than the stereo

pair (most mono tracks are held on digital media as

identical left and right). There’s also a Party mode,

069

CLASSÉ SIGMA PRE/POWER AMPS

060699

CLASSÉ SIGMA SSP SURROUND SOUND PREAMP/PROCESSOR

INPUTS: 8 × HDMI, 0 × component video,

0 × S-Video, 0 × composite video, 3 × ana-

logue stereo (1 × XLR pair), 0 × 7.1 analogue,

2 × optical digital, 3 × coaxial digital, 1 × USB

host, 1 × USB device, 1 × Ethernet

OUTPUTS: 1 × HDMI, 0 × component

video, 0 × S-Video, 0 × composite video, 0

× analogue stereo, 1 × 7.1 analogue (Front

L/R duplicated with XLR), 1 × coaxial digital

audio, 1 × 6.5mm headphone

ZONE: Nil

OTHER: 1 × RS-232C, 1 × IR in, 1 × IR out,

1 × CAN-Bus in, 1 × CAN-Bus out

DIMENSIONS (WHD): 433 × 95 × 379mm

WEIGHT: 8.21kg

FIRMWARE: 1.0.1.0

WARRANTY: Five years

PRICE: $8500

SPECIFICATIONS

070

CLASSÉ SIGMA PRE/POWER AMPS

where the music is mixed down to one channel

and sent to all speakers.

The unit comes in a mid-sized solidly-built

case with a smoothly rotating volume control

to the right, some basic connections — 6.5mm

headphone, one of the HDMI inputs, USB — to

the left, and an 11cm touch-sensitive display

screen in the middle. This screen can be used to

set up the system and select various options. It

also has a ‘Video Preview’ mode which displays

the video from the selected input.

The remote control is small and has only

eleven keys. It can navigate around the menu

system (the front screen is refl ected to your

display), although it’s relatively clunky doing so.

Much nicer is the lovely Classé app for Apple iOS

devices. It is stylish, provides all the control you

could want, and worked with perfect reliability. I

could not fi nd an Android version.

This unit — along with the two amplifi ers —

features a clever physical design: rack mounting is

easily accomplished simply by removing the side

panels, rotating them 180 degrees, and screwing

them back on. This provides rack mount ‘ears’ at

the front of each unit. Once mounted, magnetic

covers — supplied with each unit — cover the

screws to ensure things keep looking pretty.

The unit — and again the amps as well —

are fi tted with RS-232C and CAN-Bus connectivity

for full system integration, plus IR in and out.

AMPLIFIERS

The Sigma AMP2 and AMP5 are very similar to

each other, aside from the one obvious diff erence

that the former is stereo while the latter off ers

fi ve channels of amplifi cation. They even diff er in

weight by less than three hundred grams.

That’s a hint that these use Class-D amplifi ers,

since their relatively high effi ciency (typically

greater than 90%) reduces the need for bulky

heatsinks. Indeed, the cases on both units —

which are the same dimensions as that of the

SSP — are (like the SSP’s) sealed, with no air

vents. That does not mean no heat is produced.

Reasonable ventilation should be provided

since the case itself is radiating the waste heat.

Nonetheless, given that that the AMP2 is capable

of outputting up to 800 watts continuously, and

the AMP5 up to a thousand, the high effi ciency is

clear. Each amplifi er channel is rated at 200 watts

output into 8 ohms, 400 watts into four. The AMP2

can run both channels to full power into either

impedance. The AMP5 can run all fi ve channels

simultaneously to full power (ie. a kilowatt) into

8 ohms, but is only rated for two channels at a

time at 400 watts into 4 ohms. That’s because of

power supply limitations, not the least of which is

the capacity of your wall outlet.

Classé is relatively modest on the amps’

frequency response, claiming only 10Hz to

20,000Hz at -1dB into 4 ohms. This might suggest

INPUTS AND SOURCES,

NOT ALWAYS THE

SAME THING

A weird affl iction from which

many home theatre receivers

suff er is that, while fi tted with an

astonishing number of inputs,

they only have a limited number

of actual input selections. That is,

you might be able to plug a doz-

en unique pieces of equipment

into the back of the receiver, but

only use ten of them because

you’ve simply run out of input

buttons on the remote control or

front panel.

The Sigma SSP fl ips that.

There are — get this — 18 input

selections! That’s one for every

single input (including Ethernet

and USB). If that’s more than you need, you can

disable as many of them as you like. But each input is

totally assignable and each input selection is highly

confi gurable. So, for example, nothing is normally

displayed on your TV if the unit is streaming network

audio. But you can assign the video from any of the

other inputs to be displayed… perhaps a device able

to show still photos. But you can also assign any input

— audio or video or both — to more than one source

selection. So you could assign the network

to two inputs, one with video also assigned,

one without. And, of course, you can rename

the input selections to your own convenient

titles so you know what you’re getting. You

can also set to each input selection the default

audio processing.

You are not going to run out of either

inputs or input selections with this unit.

A REMOTE CONTROL IS INCLUDED

WITH THE SSP, HOWEVER THE APP

FOR iOS DEVICES IS A FAR BETTER

WAY OF NAVIGATING THE EXTENSIVE

SETUP FEATURES AND FUNCTIONS.

071

CLASSÉ SIGMA PRE/POWER AMPS

a bandwidth constrained to not much more than

that traditionally held to be audible to humans —

which is not uncommon with Class-D amps — or

it might simply refl ect some of the diffi culties in

measuring Class-D using traditional methods.

Both amps have balanced XLR inputs for two

channels, duplicated with RCA, while the AMP5

adds three more RCA inputs. There are fi ve sets of

hefty binding posts for the AMP5 and four for the

AMP2 (to facilitate bi-wiring).

Both add 12-volt trigger

I/O to the other control

connections. If you’re doing it

yourself you’ll do what I did:

just join the CAN-Bus Out of

the SSP to CAN-Bus In of an

amp with a standard Ethernet

cable. Repeat from it to the

next amp and you’re done.

The SSP will automatically

switch on and off the power

amps and provide access to

their limited settings via its

front panel.

SETTING UP

If you’re upgrading from a

regular home theatre receiver

you might be fi nd yourself

surprised: there is no auto-

Weaknesses in room acoustics

should be addressed by acoustical

treatments, not by the blunt

instrument of equalisation.

matic set-up feature. You will need to set the levels of

the loudspeakers and the speaker distances manually.

I pause here to note that the pricing of this system

is such that many people will have it professionally

installed. Still, if you’re doing it yourself, there are things

to take into account.

For one thing, while the unit has the ability to apply

EQ this also is manual, and using it seems to me to be

going kind of against the spirit of the system. The Classé

Sigma system is about purity of the signal. It should be

attached to loudspeakers worthy of it, loudspeakers

which cannot be improved by any kind of equalisation.

The surround loudspeakers should be matched to

the front left and right. Weaknesses in room acoustics

should be addressed by acoustical treatments, not by

the blunt instrument of equalisation.

So if you are doing it yourself, you should acquire a

sound pressure level meter to make sure the levels are

properly calibrated. For the rest you only need a tape

measure and the specifi cations of your loudspeakers.

For those speakers set to ‘X-Over’ (i.e. ‘Small’) you can

set separate crossover frequencies for each speaker

pair in 10Hz increments from 40Hz to 140Hz. Obviously

the system is not intended for tiny satellites, so that’s a

more than adequate range.

It was puzzling initially why the output for the front

left and right channels was so much higher than for the

other channels. Then I remembered: XLR outputs are

normally 6dB higher than single-ended RCA.

One little surprise. The HDMI output of the receiver

passes through the audio to the display device — i.e.

the TV or projector. If you’re using the former, make sure

you reduce its volume to zero.

And one possible weakness. The A/V lip sync can

apply a delay of just 99 milliseconds. Home theatre

receivers typically off er up to 500ms for the simple

reason that today’s TVs are slow. The norm for a 4K TV

is a delay of around 150 milliseconds in the video, and

some are well over 200ms. Whether this will aff ect you

depends on your display and your sensitivity to lip sync

misalignments. My particular TV works best with 150ms

delay, but at 99ms it was fi ne to my eyes.

LISTENING

Before describing the listening impressions, let me

express how well disposed to listening the control

system left me. That was very well disposed indeed.

The reason was simple: I switched a great deal between

CDs, high resolution discs — both stereo and multi-

channel — Blu-ray movies and streaming uncom-

pressed music from the network. Mostly the last.

And very soon I developed a comforting

confi dence in the system’s switching. It might sound

trivial, but with many systems when you start trying

to stream music via DLNA or AirPlay (both supported

by the SSP) there’s a long wait as though it’s deciding

whether or not it wishes to co-operate. All too often

the decision is ‘No’, leading to a bout of switching off

CLASSÉ SIGMA AMP5 FIVE CHANNEL POWER AMPLIFIER

RATED POWER: 5 × 200 watts, 8 ohms;

5 × 400 watts, 4 ohms (two channels driven)

INPUTS: 5 × analogue audio (front L/R

duplicated with XLR)

OUTPUTS: 5 pairs speaker binding posts

OTHER: 1 × RS-232C, 1 × IR in, 1 × IR out,

1 × trigger in, 1 × trigger out, 1 × CAN-Bus

in, 1 × CAN-Bus out

DIMENSIONS (WHD): 433 × 95 × 379mm

WEIGHT: 10.48kg

PRICE: $8500

WARRANTY: Five years

CLASSÉ SIGMA AMP2 TWO CHANNEL POWER AMPLIFIER

RATED POWER: 2 × 200 watts, 8 ohms;

2 × 400 watts, 4 ohms

INPUTS: 2 × analogue audio (duplicated

with XLR)

OUTPUTS: 4 pairs speaker binding posts

OTHER: 1 × RS-232C, 1 × IR in, 1 × IR out,

1 × trigger in, 1 × trigger out, 1 × CAN-Bus

in, 1 × CAN-Bus out

DIMENSIONS (WHD): 433 × 95 × 379mm

WEIGHT: 10.21kg

PRICE: $6000

WARRANTY: Five years

DISTRIBUTOR: Convoy International

on 02 9700 0111

www.convoy.com.au

SPECIFICATIONS

072

PRE/POWER AMPSCLASSÉ SIGMA

a controlled decay that leaves not the slightest

detail obscured. Loud piano is deadly on some

systems given that the peaks — on this recording

at least — can be 18dB higher than the average.

That is, if the average level is two watts, the

output voltage at the peak would be the same as

required to generate 128 watts. This system had

all the reserves it needed.

Big Brother and the Holding Company’s

‘Cheap Thrills’ was delivered from multichannel

SACD (the player decoded to PCM because this

system won’t handle DSD) with that perfect

sense of time. It was 1968, where the sound of

good recordings was dynamic yet naïve, spared

from much of the modern recording studio’s

processing, yet also revealing of the imperfections

of late 1960s equipment, including microphones.

From Schubert’s String Quintet to Primus’

‘Antipop’, the system was delicate and powerful

as required by the source material and only by

the source material, bending the loudspeakers

precisely to the system’s will.

It supported FLAC music up to 192kHz, also

Apple Lossless, AIFF and WAV, and a wide range

of lossy formats (WMA, MP3, Ogg Vorbis, AAC)

and, for AirPlay, HE-AAC and AAX and AAX+, the

formats used for Audible narrated books.

The same stood for movies. Sure, the sound

of many movies is only really there to let you

know what’s going on, but quite a few are works

of art. The punch and thrust of the gun battles

and airplanes on the runway of ‘Heat’ tests

many amplifi ers. This system just went about its

business of pounding the listening room with

well-positioned sonic blasts with no apparent

eff ort. But moving to the dreamlike surround

fi eld of ‘Atonement’, the system was equally

competent, equally at home, and quite simply

totally entrancing.

CONCLUSION

Oh my, what a wonderful system Classé has

provided with the Sigma range. It shows that

audiophile quality sound is not the sole preserve

of stereo, and equally that it is not incompatible

with reliable and convenient operation.

networks and switching them back

on, just to listen to a damned song!

Underpowered CPUs, I suppose, or

weak programming.

But with the SSP it was simply a

matter of bringing up my favourite

DLNA streaming app, selecting the SSP

as the ‘renderer’ and starting the music

playing. Or, in iOS world, choosing the

SSP as the Airplay ‘Speaker’ from iTunes

or the iPad. Within two seconds the

music was emerging, clean, pure and

with confi dence from both the system

and yours truly, the listener. I typically

ran two compact tablets: an Android

one to stream FLAC music to the

system and an iPad to control the unit.

As for the sound, the system

as a whole did precisely what was

required of it: and that is to provide

a gorgeously pure signal with

seemingly limitless levels of power

to whichever loudspeakers were

used (including some doozies of low

impedance models).

Right now, Liszt’s Hungarian

Rhapsody #2 is thundering out at

concert grand levels, yet with a

precision of attack on the notes and

CLASSÉ SI

THE APP FOR iOS IS BEAUTIFULLY

DESIGNED WHILE PROVIDING COMPLETE

CONTROL OVER THE VARIOUS FUNCTIONS.