Feliks Audio Envy Standard walnut

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

A fully balanced Single-Ended Class A topology

The Envy Standard is a transformer-coupled Single-Ended (SET) output-stage amplifier, biased in pure Class A and free of global feedback. Its circuit is fully balanced: Feliks Audio uses two custom-built 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 required after changing tubes.

The internal wiring is entirely done point-to-point in pure copper, with hand-executed soldering. This method, common in high-end tube amplifiers, extends the device’s lifespan and makes future 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 is based on a particular balance between linearity, smoothness in the upper range, and presence in the midrange. The pair mounted in SET configuration in the Envy delivers 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 300Bs. The Standard version comes with Electro-Harmonix Gold 300Bs, which provide a solid starting point and leave full scope for tube rolling, the practice of substituting tubes with other references to alter the sound signature.

Complete connectivity and preamplifier function

Three inputs are available: two pairs of unbalanced RCA and one pair of balanced XLR. The front-panel source selector lets you switch between all three.

The Envy can also serve as a preamplifier in a speaker-based listening system. It features an unbalanced RCA line output and a balanced XLR line output, both with level controlled by the front-mounted Alps Rk27 volume knob. 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 outputs are available on the front panel: one unbalanced 6.35 mm jack and one 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 presents a challenge that is rarely handled well by a single device. The Envy’s impedance selector modifies the output transformer ratio to maintain proper power transfer regardless of the load. In practice, planar headphones known for their high current demands find here a partner capable of supplying the necessary power, while high-impedance dynamic headphones remain well controlled without excessive gain.

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

Handcrafted wood and aluminum construction

The chassis combines a machined aluminum structure with an oiled wood enclosure, in keeping with 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, since 300B tubes generate heat during operation.

The internal capacitors are Mundorf EVO for coupling and Nichicon for filtering. The Alps Rk27 potentiometer controls volume with smooth action and excellent channel matching between left and right.

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

Technical specifications

Design and manufacturing

• 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