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AVID sigsum


The AVID Sigsum is a purist high current Integrated Amplifier with a separately powered built-in phono stage engineered to deliver sound quality exceeding many phonostage, pre and power amp three-separate-component set-ups.

checkboxPower output 110W both channels 8Ω, 20Hz-20KHz

checkboxLow 0.003% harmonic distortion 80% power, 8Ω at 1KHz

checkboxAVID Pulsus MM/MC Phono stage with its own regulated 35VA toroidal transformer power supply

checkboxVery large 1.1KVa main toroidal transformer with 132,000 uF capacitor power reservoir

checkboxInput sensitivity 2x greater than most preamplifiers

checkboxMaximum input voltage 2x greater than most preampliers

checkboxPurist ALPs RK50 analog potentiometer (volume control)

checkboxDual amplifier boards derived from AVID reference level amplifiers

checkboxHigh current design to drive large 4-16Ω loudspeakers

checkboxPowerful 10v rms headphone amplifier

checkboxComprehensive protection circuits

checkboxSwitchable Mono operation and mute

checkboxHeavy guage steel chasis with 20mm solid aluminum front panel

checkboxCarefully hand crafted with exacting continual test measurement

checkboxDimensions: 23.6"(w) x 22.4"(d) x 10.2"(h) Weight: 69bs

AVID Sigsum ALPS RK50 potentiometer

Exceptional preamplifier section

During evaluation of methods to control volume for the Reference and Celsus Preamplifiers, AVIDHIFI found nothing beat the non-motorized ALPS RK50 type potentiometer used in the Reference and Celsus Preamplifiers and the AVID Sigsum benefits from this potentiometer which is generally regarded as the world's best. The lowest level signals, barely above the noise floor, which would be lost in a multi-component or digital approach, remain intact in this large brass housed potentiometer which also has generous headroom thus preserving the complete full dynamic range of a signal. Motorizing the potentiometer and associated digital control led to signal loss and degradation and thus the Sigsum has manual only operation.

Two balanced XLR and two unbalanced RCA line level inputs are provided with short signal paths and the highest quality switching relays. AVID choose to limit the number of inputs so these could be engineered to a very high performance rather than providing a greater number of mediocre quality ones that are never used.

The smooth operation of the volume control and discrete output muting when switching between inputs adds a pleasant degree of quality and sophistication.

Overall operation is as simple as it gets.

AVID Sigsum Phonostage

Versatile Comprehensive Phono Stage

In addition to the four line-level inputs is a Pulsus MM/MC phono stage powered by its own toroidal power supply which is well isolated from the main amplifier section and with the advantage of a shorter signal path to the preamplifier compared to a stand alone phono stage.

Adjustable resistance, capacitance and gain up to 70dB with low noise levels (MM -81dB, MC -67dB high setting) is provided and RIAA accuracy is +/- 0.5dB over 5Hz to 70KHz.

Gain: 40dB - 50dB - 60dB - 70dB

Resistive loading: 100 - 300 - 500 - 1K - 5K - 10K - 47K Ω

Capacitance loading: 100pf - 200pf - 500pf

As an analog orientated company and leading manufacturer of turntables, tonearms and cartridges, you can be confident that the phono stage is a very good one.

AVID Sigsum massive main toroidal transformer

What makes the power amplifier section of the AVID Sigsum special?

The same philosophy of an abundance of power supply and storage reservoir capacity taken to the extreme in AVID's Reference Mono amplifiers is cascaded down in no small measure here.

The Sigsum's 1,100 VA toroidal transformer and 132,000 uF capacitance is more than many other high end integrated amplifiers and means the Sigsum does not run out of juice powering large loudspeakers in moderately sized rooms. The AVID Sigsum will preserve the dynamic range beyond its 110 watt specification more than amplifiers that while specified at twice the output power may have hardly any headroom.

Connection to the loudspeakers is made from very high quality UK made binding posts that are well spaced apart to receive banana plug type connectors as large as those found in Van den Hul's Cumulus speaker cables or to receive spade terminations that can be secured very tightly. The output stage is a high current one but the Sigsum does not run hot.

Protection is provided in the event of a fault occuring such as output short-circuit, DC offset, or if the unit exceeds its maximum operating temperature.

The heavy duty speaker binding posts are compatible with both 0.25" and 8mm spades. Four millimeter banana plugs that are over 5/8" or 17mm in length may also be used but 0.5" older style bananas plugs are not long enough.

kemela commentary

The AVIDHIFI Sigsum Integrated Amplifier sonically differentiates itself from other high end integrated amplifiers.

When auditioning HiFi components, getting a feel for what a new component is bringing to the table is sometimes more striking when you return back to the one you currently use and become aware of its limitations. Subjective listening either delights or disappoints from the objective expectations setup during online "research" by reviews or specifications.

In the case of the AVID Sigsum, after getting used to its sound, what was noticeable going back to other integrated and pre/power combos was what was missing and that sonic recognition required a bit more interpolation. Pixels of low level musical information were just missing almost reminding me of subtle magnetic tape drop-out but on a finer scale or another analogy might be where one coat of paint that is uneven and patchy not quite covering up the previous color is superimposed onto the sound modulating it. AVID's Sigsum paints a continuous uniform field within which all the texture is present and apparent leaving very little that is obscured making it far easier to get drawn into the performance because there is a stronger sense of shape of musical phrases. The more intimate artistry of breath control and vibrato is there to appreciate.

This expands with the bass which is both rhythmically punchy and powerfully deep with nimble articulation so that individual parts start, stop and dialog with greater intention giving a fluid quality and drive to the sound. It's the toe-tapping swing of jazz or the precision of an orchestra playing well together that compels you to want to conduct (when you are on your own and no one is looking of course). The midrange is clean, rich and open while the top end is sweet, correctly proportioned being neither intense or hard so timbres always sound natural.

Of course the cables speakers and source used all come into play and the Sigsum was resolving enough to elucidate differences between all of these. What always seemed to be in place, however, was a captivating performance revealing the quality of the recording imparting realism drawing you into the performance while forgetting about sound reproduction for the better recordings. All very desirable characteristics, if not what you should expect, from a high-end audio system.

The Avid Sigsum drove Spendor D7.2s, Classic 100s, KEF Reference Ones and Blades in my 22' x 18' x 9' room to the comfortable levels I listen at with no sign of difficulty, and considering the Blades have four 9" bass, midrange and tweeter drivers, the is very commendable. There are four Sanken 130 W complimentary bipolar power transistor pairs per channel and the massive power supply so this is not entirely suprising. A 300 watt Chord Ultima 5 excelled in some areas but the Sigsum held its own in others.

For an up-market simplified vinyl-based system there is not much more you could ask for and the lack of a remote is not really an issue.

But what about digital sources?

By utilizing a DAC with good volume control - such as the Chord Electronics Hugo TT2 - you can have your cake and eat it using the remote that comes with the DAC to volume level between digital sources (particularly with streaming where armchair volume control is a must.) Using this DAC via one of the Sigsum's XLR inputs and setting the analog volume control of the Sigsum mid-way was testament to how the ALPs potentiometer got out of the way and the Sigsum sounded on par with a good power amplifier.
It's probably not a bad idea to separate the digital from the analog anyway and use a good isolating power conditioner as digital electronics can introduce noise to your mains supply and contaminate the other components.


It is larger than some hifi stands can house and you have to be careful lifting it on your own. Critics would raise the issue of the DIP switches being underneath which is more of an inconvenience than anything most could not live with - personally I'd be far more critical of heat produced and general inefficiency of tube amps.
Oddly enough its talented dynamic range suggests occasionally that perhaps there are even greater dynamics to be created in your room - something the even more capable AVIDHIFI separates can no doubt provide (there is however a preamp out if you want a bit more power or care to bi-amp).


I'm rather glad Conrad Mas stuck to his guns and did not compromise this very engaging integrated amplifier by caving in and including remote control which surely otherwise would have taken away some of the magic. Once you hear the AVID Sigsum and compare to other high end integrateds, you too will be glad, and this bold amplifier should not be dismissed for its lack of a remote right out of the gate. It's an original and a lot of thought went into achieving its objectives.

There have been some recent positive reviews but it's not yet been heard at many trade shows and deserves more attention. If you are an experienced HiFi enthusiast perhaps looking to simplify down to your final easy-to-use no-nonsense HiFi system, and especially if vinyl is important, it's well worth checking out. If you are at the beginning of your HiFi journey and your budget can't quite stretch to it, the sibling AVID Integra uses the same amplifier boards at about half the cost.

You can audition both at kemela.

U.S Retail Price: $19,995 black or silver finishes.


AVID Sigsum Integrated Amplifier
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