Sigma 170i
Integrated Amplifier

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.

Product Brochure
Sigma 170i
  • 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




  • Wattage

    85 watts/channel

    Power Bandwidth

    13 Hz to 70 kHz


    Four line level inputs plus one Cinema Bypass input
    Optional balanced input on Input 4
    Optional MM/MC phono on Input 1


    Connections to precisely match loudspeaker loads of 4, 8 and 16 ohms


    4x KT88

    5x 12AU7A

    1x 12AX7A


    May be factory-configured for operation at 100, 120, 220, or 230/240 volts

    Power Cord

    Detachable power cord, standard IEC power receptacle

    Remote Control

    Volume & Mute, included


    Hand-rubbed gold-flake gloss black lacquer fascia with chrome knobs standard.

    Hand-rubbed metallic gloss silver lacquer fascia with chrome knobs special order with additional cost.


    Two years parts and labor, excluding tubes (USA, see manual for full details)

    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.)

    Phono option:


    37 dB MM
    57 dB MC

    Frequency Response

    RIAA +/‑ 0.2 dB

    Residual Noise

    3 mV at output (S/N ratio approx. 69 dB)


    117 mV @ 1 kHz = 8 volts RMS output; 460 mV @ 10 kHz

    Variable loading

    Yes for MC


    2x 12AX7A

    *Specifications subject to change without notice.


    “Damn, this is a fine amp... it laughed at everything I could throw at it, delivering via Sasha DAWs the kind of levels and soundstage which did justice to the scale of both 'big band' and classical orchestras. It's a love letter to the much-revered KT88, and it left me stunned.”
    Ken Kessler - hi-fi news, September 20, 2021

    “If you’re looking for the “tube magic,” the Valve Amplification Company Sigma170i has it and then some.”
    Lee Shelley - Part Time Audiophile, July 26, 2020