Ayre KX-5 Twenty Preamp

Description

The Ayre KX-5 Twenty is a reference-quality analog preamplifier from Ayre Acoustics of Boulder, Colorado. Introduced in 2015 to mark the company’s twentieth anniversary, it incorporates technologies developed for Ayre’s more expensive KX-R series into a more compact and comparatively accessible design. Built for serious two-channel systems, the KX-5 Twenty emphasizes exceptionally low noise, accurate tonal reproduction, wide dynamic range, and convincing spatial presentation. Its fully balanced, discrete circuitry and minimalist aluminum enclosure reflect Ayre’s longstanding commitment to engineering simplicity and musical transparency.

One of the KX-5 Twenty’s most important innovations is its Variable Gain Transconductance (VGT) volume-control circuit. Rather than using a conventional potentiometer or attenuator to discard unwanted portions of the audio signal, VGT changes the gain of the amplification stage itself. The design employs 46 discrete volume steps, each approximately 1.5 dB, allowing the signal path to maintain an optimized operating condition across the volume range. By avoiding traditional attenuation, Ayre aims to preserve resolution, minimize noise, and retain subtle musical information even at lower listening levels.

The preamplifier’s EquiLock gain stage and Diamond output stage further distinguish its design. EquiLock circuitry is intended to improve linearity and reduce distortion as operating conditions change, while the Diamond output stage provides current gain without adding a conventional voltage-gain stage. The entire signal path uses fully balanced, zero-feedback, discrete circuitry. Ayre’s engineering philosophy avoids global negative feedback, relying instead on circuit topology and component selection to achieve low distortion and stable performance. A linear analog power supply with AyreLock regulation and the company’s AyreConditioner radio-frequency interference filter supports consistent operation.

Connectivity is comprehensive for a dedicated analog preamplifier. Six inputs are provided: four balanced XLR connections and two single-ended RCA connections. Both balanced and unbalanced outputs are available, allowing compatibility with a broad range of power amplifiers. The unusually high input impedance—specified at 1 megohm for unbalanced inputs and 2 megohms for balanced inputs—minimizes loading on source components. Input-ground switching helps isolate connected sources, while AyreLink provides communication with compatible Ayre equipment. The KX-5 Twenty is strictly an analog line preamplifier, however, and does not include a DAC, phono stage, or digital inputs.

Sonically, professional reviews have emphasized the KX-5 Twenty’s exceptional clarity without a harsh or clinical character. Stereophile reviewer Art Dudley praised its “remarkable and utterly nonclinical clarity” and “commandingly good spatial performance.” SoundStage! Hi-Fi’s Aron Garrecht described it as remarkably transparent and refined, comparing its presentation favorably with much more expensive reference preamplifiers. These assessments suggest a component that combines fine resolution with natural instrumental timbre, precise imaging, and an unusually quiet background.

The KX-5 Twenty’s physical design is understated but luxurious, with a brushed aluminum faceplate, central display, and substantial rotary controls. Weighing 23 pounds, it is relatively compact for a preamplifier of this class. Its one notable drawback is usability: reviewers have criticized the setup process and owner’s manual as less intuitive than expected for a component at this price. Nevertheless, for listeners prioritizing sound quality and owning a high-resolution source and capable power amplifier, the KX-5 Twenty remains a compelling high-end preamplifier.

Review quotes

“the best preamplifier I have reviewed”

— Aron Garrecht, SoundStage! Hi-Fi, in his assessment of the KX-5 Twenty.

“remarkable and utterly nonclinical clarity”

— Art Dudley, Stereophile, describing its sonic character.

“Music that you thought you knew well sounds fuller, more vibrant, more ‘real’.”

— Deon Schoeman, Audio Video SA, reviewing the KX-5 Twenty with Ayre’s VX-5 Twenty power amplifier.

Product specifications

• Manufacturer: Ayre Acoustics

• Model: KX-5 Twenty

• Type: Fully balanced solid-state stereo line preamplifier

• Country of manufacture: United States

• Introduction: 2015

• Circuit topology: Fully discrete, zero-feedback design

• Gain stage: Ayre EquiLock

• Output stage: Ayre Diamond circuit

• Volume control: Variable Gain Transconductance (VGT)

• Volume adjustment: 46 steps, approximately 1.5 dB per step

• Frequency response: DC–250 kHz

• Maximum input level: 8 V RMS unbalanced; 16 V RMS balanced

• Input impedance: 1 MΩ unbalanced; 2 MΩ balanced (1 MΩ per phase)

• Gain: Variable to match the required output level without conventional attenuation

• XLR input polarity: Pin 1 ground, pin 2 positive, pin 3 negative

• Inputs: Six total — four balanced XLR and two single-ended RCA

• Outputs: Balanced XLR and single-ended RCA

• Power supply: Linear analog supply with AyreLock regulation

• Noise suppression: AyreConditioner power-line RFI filter

• System integration: AyreLink communication system

• Circuit-board material: High-speed audio-grade substrate

• Power consumption: 40 W in operating mode; 60 W with volume control active

• Dimensions (W × H × D): 17.25 × 3.75 × 13.25 inches (440 × 95 × 337 mm)

• Weight: 23 lb (10.5 kg)