VAC Sigma 170i Integrated Amplifier
Best integrated amplifier for audiophiles seeking classic tube warmth and reliability.
The VAC Sigma 170i Integrated Amplifier, released in 2021 and now discontinued, stands out as a sophisticated audio component. It was the first integrated amplifier to feature VAC's patented iQ Continuous Intelligent Automatic Bias System, ensuring optimal output tube performance, enhanced detail, and extended tube life. Praised for its musicality, sweet treble, and excellent midrange, it masterfully balances grace with dynamic power. Its luxurious build quality, point-to-point wiring, and intelligent performance management deliver a classic tube sound experience with modern reliability.
$10000.00
Owner Satisfaction
4.7
/ 5
Category Rank
421
/ 1684
#421 in Power Amplifiers
Price vs Category Average
+21%
Above average
Wattage
858
/ watts/channel into ohms
Who it's for
- Vinyl enthusiasts wanting a streamlined, all-in-one analog setup
- Audiophiles seeking an immersive and holographic listening experience
- Listeners with power-hungry or low-sensitivity speaker systems
Who should skip it
- Budget-conscious buyers looking for entry-level audio gear
- Owners preferring low-maintenance, solid-state amplification
- Users with limited rack space or small, poorly ventilated rooms
Performance breakdown
Tube Maintenance
The iQ system eliminates manual bias adjustments for effortless tube longevity.
Sonic Character
Delivers a lush, classic tube sound with exceptional midrange clarity.
Build Integrity
Hand-wired point-to-point construction ensures heirloom-grade durability and performance.
Dynamic Authority
Eighty-five watts per channel provides ample headroom for demanding musical passages.
Feature Set
Pure analog design prioritizes sonic purity over modern digital conveniences.
Operational Simplicity
Lack of remote control requires a more tactile, hands-on listening experience.
Key Specs
Wattage
85 watts/channel into 8 ohms
Power Bandwidth
13 Hz to 70 kHz
Tubes
4x KT88, 5x 12AU7A, 1x 12AX7A
Dimensions (H x W x D)
8 x 18 x 17.3 in. (203 x 457 x 440 mm)
Shipping Weight
71 lbs. (32 kg)
Frequency Response
RIAA +/- 0.2 dB
Signal-to-Noise Ratio
approx. 69 dB
Inputs
Four line level inputs plus one Cinema Bypass input
Features
- Patented iQ automatic bias system for optimal tube performance
- Delivers a blend of grace and dynamic power
- Sweet treble and excellent midrange reproduction
- Point-to-point hand wiring construction
- Integrated amplifier design
- Stereo channel configuration
- Luxurious build quality and premium parts
- Class A operation for superior sound
What customers say
The VAC Sigma 170i Integrated Amplifier earns high praise for its exceptional musicality and build quality. Owners consistently highlight the tube design's contribution to a rich, holographic soundstage and natural warmth. Vocal and acoustic reproduction in the midrange is a standout feature, offering texture and depth often unmatched by solid state alternatives. The unit features robust, heirloom quality construction reflecting meticulous craftsmanship. While positioned in the luxury segment, users feel the profound sonic performance justifies the investment, viewing it as an end game component. It successfully merges classic tube character with modern detail retrieval, creating a deeply satisfying listening experience.
Know before you buy
The iQ system automatically monitors and adjusts the bias of the output tubes in real-time. This ensures the tubes always operate at their optimal performance level, which results in better sound quality and significantly extends the lifespan of your vacuum tubes.
No, the Sigma 170i is a pure analog integrated amplifier. It does not feature an internal digital-to-analog converter or a phono stage, so you will need to use external components for digital sources or vinyl playback.
Class A operation is prized for its linearity and lack of crossover distortion, which contributes to the amplifier's signature sweet treble and rich, detailed midrange. It provides a highly musical and refined sound profile that is characteristic of high-end tube amplification.
Yes, the amplifier includes a dedicated Cinema Bypass input. This allows you to integrate the unit into a home theater setup, letting your surround sound processor control the volume for the front left and right channels while using the VAC for high-quality stereo amplification.
While the iQ system manages bias automatically, you are still using a tube-based design with 10 total tubes. You should expect to replace the tubes periodically as they wear out, though the iQ system helps ensure they last as long as possible before needing replacement.
With 85 watts per channel and a robust power bandwidth, the Sigma 170i is capable of driving a wide range of speakers with authority. However, it is specifically optimized for an 8-ohm output impedance, so it performs best when matched with speakers that maintain a stable impedance curve.
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$10000