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VAC Amps Sigma 170i
The new VAC Sigma 170i is the world’s first integrated amplifier with the patented iQ Continuous Intelligent Automatic Bias System. The iQ System holds the true idle point of the output tubes perfectly steady under all conditions, increasing detail & dynamics, lowering distortion & noise, prolonging tube life, and protecting the amplifier. Integrated amplifiers are a great lifestyle choice, and VAC lets you have all of the benefits of tubes without the worry.
With optional MM/MC phono and balanced inputs, the 85 watt/channel Sigma 170i is ready to be the heart of your high end musical experience.
Features include:
- Pure vacuum tube audio circuitry
- 85 watts/channel into 4, 8, and 16 ohm speakers
- Cinema bypass mode for tie in to home theater
- Remote control
- True Class A triode tube line stage
- Pure analogue volume control
- Four inputs
- Optional MM/MC phono with adjustable MC loading
- Optional balanced input
- Optional perforated tube cage (required for CE countries)
- Fascia available in black or silver metal flake paint
- Hard chrome knobs and iQ display bar
- Gold Lion KT88 output tubes
- Premium Cardas RCA & speaker connectors
- Hand made in the United States by VAC
The Special Edition version uses the Statement Series line input transformers with the balanced option, and incorporates exotic capacitors and resistors in key circuit locations for a larger, more vivid, detailed, and organic presentation
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Professional Reviews 93/100
Deliciously Crispy
Sound Quality
95/100
Build Quality
93/100
Features Connectivity
90/100
Value for Money
90/100
The VAC Sigma 170i marries classic valve richness with startling bass authority, spacious imaging and clean, fleet-footed treble. HiFi News admired its effortless scale and finely defined vocals, while HiFi Choice found its lush musicality equally convincing with orchestral grandeur and visceral rhythm. With 85 watts per channel and flexible speaker taps, it is a commanding, beautifully composed KT88 integrated.
What Reviewers Are Saying
Pros
Combines lush valve musicality with extended, detailed treble that remains free of edge.
Delivers unusually weighty, well-defined low bass and convincing dynamic authority for a tube integrated.
Creates an expansive, airy soundstage with exceptionally clear vocals and convincing orchestral scale.
Multiple impedance taps and automatic tube-bias monitoring support broad speaker compatibility and easy ownership.
&
Cons
Balanced input, MM/MC phono stage and protective valve cage are costly optional extras.
The supplied remote control is limited to volume and mute functions.
SOUND QUALITY PERFORMANCE 95/100
The Sigma 170i is praised for combining classic valve richness with unusually firm bass, speed and large-scale authority. Reviewers also highlight its clean treble, natural vocal reproduction, strong emotional communication and expansive sense of recorded space.
Transparency Resolution
94/100
Hi-Fi Choice and Hi-Fi News describe strings as extended, detailed and exceptionally fast, without screech or unwanted edge. Vocal lines are portrayed with striking definition, while the amplifier remains revealing even with less-than-audiophile recordings.
Tonal Balance Musicality
95/100
Reviewers repeatedly describe a lush, cosseting and thoroughly musical valve presentation, with sweet treble, excellent midrange bloom and rich vocal tone. Audiophilepure also found timbres more natural than merely warm, suggesting that the amplifier avoids excessive tube coloration.
Dynamics
94/100
The 170i is consistently credited with pairing valve grace to real grunt, treating dynamic shifts with conviction and emotional force. Reviewers found it more powerful than its rating suggests, with solid attacks and sufficient composure for demanding Wilson Sasha DAW loudspeakers.
Soundstage Imaging
96/100
Space, air and concert-hall scale are among the most emphatic strengths reported. Hi-Fi News heard exceptionally well-defined vocals and a room-defying recreation of orchestral scale, while also praising the amplifier's ability to maintain that presentation across very different loudspeakers.
Assessments of Build Quality, Usability, and Overall Propositions.
Build Quality
93/100
Audiophilepure describes the Sigma 170i as hand-built, luxurious and intended to last at least a lifetime, with carefully considered details. The available glass-and-metal valve cage adds practical protection, although it is an expensive option rather than standard equipment.
Features Connectivity
90/100
The amplifier provides four line inputs, Cinema Bypass, remote volume and mute control, impedance-matched 4, 8 and 16-ohm speaker connections, and preamp outputs. The reviewed fully equipped configuration adds balanced XLR input capability and an MM/MC phono stage with selectable MC loading, though these are paid options and the remote is limited to level and mute.
Value for Money
90/100
At $10,900/£10,000, the Sigma 170i is undeniably a luxury purchase, and the optional phono, balanced-input and cage packages increase the outlay substantially. Still, Audiophilepure explicitly finds value in its hand-built, long-lived and carefully considered execution, while the listening reports support performance commensurate with its premium position.
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Authorized dealers for VAC Amps Sigma 170i
- The ASOC Gallery of Fine Audio — in-store — Stratford, Ontario, Canada (website)
- American Sound — in-store — Richmond Hill, Ontario, Canada (website)
- Audio compositions — in-store — Newark, Delaware, United States (website)
- Audio Salon — in-store — Boca Raton, Florida, United States (website)
- Dr Vinyl — in-store — Middle River, Maryland, United States (website)
- Echo Audio — online and in-store — Portland, Oregon, United States (website)
- Editors Choice HiFi — in-store — Paola, Kansas, United States (website)
- Elite Audio Systems — in-store — San Francisco, California, United States (website)
- HiFi Loft — in-store — New York, New York, United States (website)
- HIFI SOLUTION — in-store — Chandon, Auvergne-Rhône-Alpes, France (website)
and 12 more verified dealers