The Cayin Soul 170C succeeds the A-845Pro model launched in 2018 for the brand’s 25th anniversary. This 20 kg preamplifier relies on eight carefully selected tubes (Tung-Sol and Mullard) and a fully balanced Class A circuit. Its adjustable negative feedback system allows you to adapt the sonic character from the listening position. The chassis combines anodized aluminum and North American black walnut, while the mixed RCA and XLR connectivity ensures integration into most configurations.
The Soul 170C employs eight tubes distributed according to their functions. The two 17AX4GT tubes handle AC rectification, recognized for their low internal resistance. Two 6CA7 tubes manage voltage regulation independently for each channel, contributing to the 90 dB stereo separation.
Line amplification relies on an unusual combination: two ECC83 (Mullard CV4004/12AX7 variant) and two 6SN7GTB Tung-Sol tubes. The ECC83 tubes provide high gain and linearity, while the 6SN7GTB tubes handle higher currents while maintaining low distortion. This eight-tube configuration for a preamplifier is rare and demonstrates Cayin’s choice to entrust each critical stage to tube technology.
Each Soul 170C is manually assembled using the point-to-point wiring technique, which avoids printed circuit boards. Connections are made with heavy-gauge silver-plated cables, minimizing signal loss. This time-consuming method guarantees audio path purity.
The toroidal power transformer and EI output transformer are designed and hand-wound in Cayin’s workshops. The oversizing of these components allows full exploitation of the tubes’ potential. The motorized volume potentiometer comes from Japanese manufacturer ALPS, a reference for its precision. The ceramic tube sockets offer better thermal insulation than plastic models.
A soft-start circuit delays the voltage rise by one minute at power-on, protecting the tubes from thermal shock. A removable cage covers the tubes to prevent accidental contact.
The negative feedback (NFB) system adjusts to two positions via the infrared remote control. In Low NFB mode, the gain reaches 17.5 dB and the sonic presentation remains open and fluid, favoring naturalness. In High NFB mode, the gain drops to 16 dB and the circuit tightens linearity, reducing distortion for a more precise and analytical rendering.
This function allows you to adapt the preamplifier to the power amplifier’s character, the room’s acoustics, or the type of music. Being able to switch from one mode to another from the listening position transforms this technical adjustment into a genuine comparative listening tool.
Five line inputs equip the Soul 170C: four RCA pairs and one XLR pair. On the output side, one RCA pair and one XLR pair allow driving amplifiers in single-ended or balanced configuration. The outputs deliver up to 8 V RMS in RCA and 16 V RMS in XLR, offering comfortable headroom even for sensitive amplifiers.
The infrared remote control manages all functions: input selection, volume, and NFB mode. The unit memorizes the last settings before shutdown. The dimensions (430 × 445 × 239 mm) and 20 kg weight require a stable stand. The solid anodized aluminum front panel and black walnut side panels require artisanal work for each unit.
The frequency response extends from 8 Hz to 100 kHz (±3 dB) in RCA, but is limited to 35 kHz in XLR. This choice influences the reproduction of the highest harmonics depending on the output used. The total harmonic distortion (THD) reaches 0.02% at 2 V RMS, an honorable value for a tube preamplifier. The signal-to-noise ratio of 100 dB (A-weighted) guarantees a silent noise floor. The 75 W power consumption remains reasonable, although the unit heats up continuously like all tube equipment.
Can the Soul 170C’s tubes be replaced with other models?
Replacement is possible, but Cayin strongly recommends using matched and tested tubes, ideally supplied by the manufacturer. The 6CA7 and 17AX4GT tubes require rigorous selection to avoid any imbalance in the power supply. Poor matching can damage the circuit.
Does the Soul 170C require warm-up time?
Like all tube equipment, the Soul 170C benefits from stabilization time. The soft-start circuit already imposes a one-minute delay, but it is advisable to wait 15 to 30 minutes before critical listening. This delay allows the tubes to reach their optimal temperature.
What’s the difference between the RCA and XLR outputs?
The XLR output delivers double the voltage of the RCA output (16 V versus 8 V RMS), useful for less sensitive amplifiers. However, its frequency response is limited to 35 kHz versus 100 kHz in RCA. The choice depends on the power amplifier and tonal preferences.
Does the Soul 170C pair better with tube or solid-state amplifiers?
The Soul 170C drives both tube and solid-state amplifiers equally well. Its adjustable negative feedback system precisely allows adapting the behavior to the amplifier’s character. Low NFB mode often suits sensitive tube amplifiers, while High NFB mode can match more analytical solid-state amplifiers. The choice depends on the complete system and personal preferences.
Can the Soul 170C be used with modern digital sources?
Absolutely. The Soul 170C accepts any source delivering an analog line signal: DAC, network player, CD player, turntable with phono preamplifier. The five inputs allow connecting multiple sources simultaneously and switching between them via the remote control. The XLR inputs make it a good partner for high-end DACs equipped with balanced outputs.
Detlef
Very fast delivery !!!!!!! very good product !!!!!! Perfect thank you very much !!!!!!
Comment from April 07, 2026 — Experience from March 26, 2026
Rob
Really beautiful and already sounds amazing, and over time it will only get better as the tubes burn in/break in.
Comment from January 14, 2026
