SONIC FRONTIERS SFL-2

Pre owned. In good conditions. Shows signs of wear. Original packaging not included.

The Sonic Frontiers SFL-2 is a fully balanced vacuum-tube line preamplifier, made in Canada in the mid-1990s. It stands out for its dual-chassis design, a deliberate engineering choice aimed at minimizing background noise by physically separating the power supply from the audio circuitry.

The SFL-2 features five unbalanced RCA inputs and one balanced XLR input. Outputs are available in both unbalanced and balanced formats, with the balanced outputs providing an additional 6 dB of gain. Volume is controlled via a 23-step analog attenuator, offering precise channel matching thanks to careful manual calibration during assembly. The steps are generally in 3 dB increments, with an additional -1.5 dB switch allowing for finer adjustment.

In terms of audio performance, the preamp shows a noticeable difference in total harmonic distortion (THD) levels between unbalanced and balanced configurations, delivering its best results with balanced input and output.

The sound is typical of high-end tube electronics: warm, harmonically rich, yet also detailed and transparent. Build quality is outstanding, with a solid and heavy chassis that immediately conveys durability and reliability. Its inclusion in Stereophile’s prestigious Class A and its feature on respected vintage audio site The Vintage Knob underscore its status as a reference-grade component, sought after both for its sonic performance and collector value.

Technical specifications:

• Vacuum-tube line preamplifier with fully balanced and differential circuitry; outboard power supply; remote control of all functions with 0.5 dB adjustment steps for volume and balance
• Inputs: 2 balanced line-level (XLR); 4 unbalanced line-level (RCA)
• Outputs: 2 balanced (XLR); 2 unbalanced (RCA); "HeadRoom" processed headphone output; buffered tape loop
• Common Mode Rejection Ratio (CMRR): better than 60 dB
• Total Harmonic Distortion (THD): less than 0.01%
• Preamplifier dimensions: 19" W × 4.5" H × 14.25" D (48.3 cm × 11.4 cm × 36.2 cm)
• Power supply dimensions: 9" W × 4" H × 13" D (22.9 cm × 10.2 cm × 33 cm)
• Total weight: 33 lbs (15 kg)