Sigma II

About the Sigma II

The California Audio Labs Sigma II is a tube DAC and analog processor that features a direct-coupled 12AX7 tube output stage, delivering a warm and engaging sound signature. It supports 24-bit/96kHz digital inputs via S/PDIF on TosLink and RCA connectors. The unit is designed to be left on for optimal performance, requiring about 30 minutes to warm up. It has a simple, no-nonsense design with minimal controls, including a front-panel input selector switch and an illuminated input signal indicator. The Sigma II offers a frequency response of 5Hz to 22kHz ±0.5 dB, a signal-to-noise ratio of 105 dB (A-weighted), and total harmonic distortion below 0.005%. It outputs a maximum of 2.0V RMS with an output impedance of 2k ohms and requires a minimum load of 10k ohms. The unit consumes 18 watts of power and measures 8.5" W x 4" H x 12.5" D, weighing approximately 10 lbs. It is highly regarded for its musicality, timing, and analog warmth, though it may not match modern solid-state DACs in soundstage depth or resolution. The Sigma II was originally It remains a sought-after vintage DAC for audiophiles who appreciate tube sound characteristics.