Feliks Audio Envy Standard oak

A Pure Class A headphone amplifier built around the 300B triode, handcrafted in Poland, that easily handles both dynamic headphones and high-end planar models. The family-run brand Feliks Audio, active for more than twenty years, delivers here its most ambitious project: a fully balanced, zero-feedback device that delivers up to 8 watts per channel into an impedance optimized for headphones between 16 and 600 ohms.

A fully balanced Single-Ended Class A topology

The Envy Standard is an amplifier with a transformer-coupled Single-Ended (SET) output stage, biased in pure Class A and without global feedback. Its circuit is fully balanced: Feliks Audio uses two custom-spec Lundahl transformers to generate the differential signal from an unbalanced input or to process the XLR signal directly at the input. Tube biasing is automatic, which simplifies maintenance: there is no bias adjustment to perform after changing tubes.

The internal wiring is entirely point-to-point, in pure copper, with hand-executed soldering. This method, common in high-end tube amplifiers, extends the lifespan of the device and makes later servicing easier. It also avoids the grounding constraints inherent to printed circuit boards and allows for more direct signal paths.

The choice of the 300B triode

The 300B is a directly heated triode introduced in 1938 by Western Electric for cinema amplifiers. Its reputation comes from a particular balance between linearity, smoothness in the upper spectrum, and presence in the midrange. The pair mounted in SET on the Envy provides 8 watts per channel, which is more than enough for the most power-hungry planar headphones, including those whose sensitivity drops below 85 dB/mW.

Two PsVane CV-181 Mk2 tubes (6SN7 equivalent) handle the preamplification stage upstream of the 300B tubes. The Standard version comes with Electro-Harmonix Gold 300B tubes, which provide a good starting point and leave full latitude for tube rolling, a practice consisting of replacing the tubes with other references to modify the sound signature.

Comprehensive connectivity and preamplifier function

Three inputs are available: two pairs of unbalanced RCA and one pair of balanced XLR. The source selector on the front panel allows switching between the three.

The Envy can also serve as a preamplifier in a speaker listening system. It features an unbalanced RCA line output and a balanced XLR line output, whose level is regulated by the Alps Rk27 volume knob located on the front panel. The stated maximum output level remains high (up to 10 V RMS), making it compatible with most power amplifiers or active speakers on the market.

On the headphone side, two sockets are accessible on the front panel: an unbalanced 6.35 mm jack and a balanced 4-pin XLR. A three-position impedance selector adjusts the secondary transformer ratio to optimize coupling with headphones from 16 to 600 ohms.

Compatibility with planar and dynamic headphones

The impedance gap between a 600-ohm dynamic headphone and a 16-ohm planar headphone represents a challenge rarely handled well by a single device. The Envy’s impedance selector changes the output transformer ratio to maintain proper power transfer regardless of the load. In practice, planar headphones known to be current-hungry find here a partner capable of supplying the necessary power, while high-impedance dynamic headphones remain under control without excessive gain.

The stated total harmonic distortion is 0.5% at 5 V into 600 ohms and tops out at 5% at full power. These values correspond to the usual orders of magnitude for a Class A SET: 2nd-order harmonics dominate and contribute to the “tube” signature sought by enthusiasts of the genre. This trade-off must be accepted to benefit from the timbre and dynamics specific to this topology.

Handcrafted construction in wood and aluminum

The chassis combines a machined aluminum structure with an oiled wood enclosure, in the aesthetic tradition of high-end tube amplifiers. Weighing around 15 kg, the Envy is not designed to be moved frequently: its place is on a dedicated, well-ventilated piece of furniture, as the 300B tubes generate heat during operation.

The internal capacitors are Mundorf EVO for coupling and Nichicon for filtering. The Alps Rk27 potentiometer manages volume with a smooth feel and excellent matching between the left and right channels.

A touch button on the front panel manages standby mode, and a physical switch on the rear completely cuts the power. An LED on the front panel indicates operating status. The tubes are protected by small removable grilles, useful for preventing accidental burns, but which can be removed to fully enjoy the aesthetics of the tubes in operation.

Technical specifications

Design and construction

• Amplifier type: Pure Class A, SET, fully balanced
• Handcrafted point-to-point wiring
• Internal wiring in pure copper
• Machined aluminum chassis, classic wood finish
• Made in Poland

Connectivity

• Inputs: 2x RCA, 1x XLR
• Line outputs: 1x RCA (unbalanced), 1x XLR (balanced)
• Headphone outputs: 1x 6.35 mm jack, 1x 4-pin XLR

Tubes (matched)

• Power stage: 2x 300B PsVane
• Preamplification stage (drivers): 2x PsVane CV-181 Mk2 (6SN7)

Internal components

• Capacitors: Mundorf EVO / Nichicon
• Transformers: Lundahl built to specification

Audio performance

• Frequency response: 8 Hz – 100 kHz
• Output power: 8 W
• Total harmonic distortion (THD)
  • 0.5% (600 ohms, 5 V)
  • 5% maximum (8 W)
• Optimal headphone impedance: 16 – 600 ohms
• Sound signature: warm, rich, dynamic
• Compatibility: high-end dynamic and planar headphones

Standard equipment

• 300B Electro Harmonix Gold power tubes

Physical characteristics

• Dimensions (W x H x D): 355 x 245 x 333 mm
• Weight: approximately 15 kg