NAD C399

The NAD C399 is an integrated amplifier from the Classic series, delivering 180 watts per channel. It incorporates technologies derived from the Masters series, while maintaining a design focused on essentials—a hallmark of the brand since its founding in 1972. Its digital architecture notably includes a high-resolution DAC, and it is engineered to deliver high performance in an integrated format.

Hypex nCore Amplification: Where Measurement Meets Emotion

At the heart of the C399 beats the Hypex HybridDigital nCore amplification module, a technology that represents the culmination of decades of research in digital amplification. Contrary to common misconceptions about class D, this architecture surpasses traditional linear amplifiers in all measurable parameters, while preserving the musical qualities sought by audiophiles.

The nCore module operates on a fifth-order, controlled self-oscillation principle, without hysteresis, with a feedback loop taken exclusively from the speaker output. This approach ensures perfect adaptation to the actual load, regardless of the impedance of the connected speaker. The damping factor, exceeding 150 up to 6.5 kHz, provides firm control over the drivers, which is especially beneficial in the bass range.

NAD doesn’t just integrate the standard Hypex module. The company holds a special license allowing it to directly oversee manufacturing according to its own specifications. The switching power supply, specifically designed by NAD, replaces the usual Hypex supply. This customization results in increased stability with difficult loads and an impressive reserve of instantaneous current: over 26 amperes at 1 ohm for 1 millisecond.

Total harmonic distortion remains below 0.02% across the entire audio band, dominated by second and third-order harmonics, which are perceived as musically consonant. The signal-to-noise ratio exceeds 106 dB, pushing any background noise into inaudibility, even with high-sensitivity speakers.

ESS Sabre Digital Conversion: Transparency in Service of Music

The ESS Sabre ES9028 32-bit digital-to-analog converter is a judicious choice for the C399. This chip, identical to the one used in the Masters M10 and M33 models, offers exceptional resolution up to 384 kHz. More than just a numbers game, this capability ensures uncompromised conversion of current and future high-resolution formats.

Jitter management—a scourge of digital systems that blurs temporal precision—reaches negligible levels here. Measurements reveal remarkable clock stability, preserving spatial coherence and the naturalness of timbres. The four S/PDIF inputs (two coaxial and two optical) accept signals up to 24 bits/192 kHz, more than covering home audio needs.

The HDMI eARC input deserves special mention. This interface, still rare on stereo amplifiers, allows seamless integration with modern TVs. Movie and series sound thus benefits from the C399’s audio quality, without multiplying remotes or complicating cabling.

A Phono Preamplifier That Honors Vinyl

The C399’s moving magnet phono stage exceeds typical expectations for an integrated circuit. Based on NAD’s standalone PP2e preamplifier, it incorporates several patented innovations. The RIAA curve, with extreme precision, faithfully restores the tonal balance etched into the grooves. The exceptionally high signal-to-noise ratio preserves the subtlest nuances.

A distinctive feature: the infrasonic suppression circuit. This function, absent from many high-end preamplifiers, eliminates parasitic frequencies below 20 Hz generated by warped records and mechanical resonances. Unlike traditional high-pass filters that affect audible bass, NAD’s solution preserves the extension and dynamics of musical low frequencies.

The generous overload margin accommodates high-level pressings without clipping. The coupling capacitors, selected for their sonic neutrality, preserve the signature of each cartridge. The standardized input impedance ensures optimal compatibility with the majority of MM cartridges on the market.

MDC2: Continuous Evolution as a Philosophy

The Modular Design Construction technology, introduced by NAD in 2007, reaches its second generation with the C399. The two MDC2 slots on the rear radically transform upgrade possibilities. Unlike the first generation, which was limited to one-way updates, MDC2 allows bidirectional communication between module and amplifier.

The BluOS-D module perfectly illustrates this potential. Beyond high-resolution streaming up to 24 bits/192 kHz via Wi-Fi or Ethernet, it brings Dirac Live room correction. This function analyzes the listening room’s acoustics using a supplied calibrated microphone, then applies custom-calculated corrections. Room modes—those resonances that color the bass—are neutralized without affecting the naturalness of the musical message.

The bidirectionality of MDC2 is especially relevant here: Dirac Live applies to all sources connected to the C399, both digital and analog. Five memory profiles allow you to adapt the correction according to listening position or room state (for example, curtains open or closed).

BluOS also transforms the C399 into a link in a sophisticated multiroom ecosystem. The control app, available on all platforms, provides access to over twenty streaming services, several of which offer lossless and high-resolution streams. Native compatibility with Spotify Connect, Tidal Connect, and Apple AirPlay 2 simplifies integration into existing digital environments.

Connectivity Designed for the Modern User

The connection section reveals careful consideration of contemporary usage. The two pairs of RCA line inputs use low-noise buffer stages, preserving the integrity of analog signals. The preamplifier outputs allow the addition of an external power amplifier or powering a multi-zone system.

The two independent subwoofer outputs make it easy to integrate subwoofers, with the possibility of optimizing their placement without wiring constraints. This attention to practical details characterizes NAD’s approach: technology serving the user, never the other way around.

Bidirectional aptX HD Bluetooth deserves to be highlighted. Beyond high-quality reception from mobile devices, transmission to Bluetooth headphones preserves audio quality. This feature, rare on integrated amplifiers, meets new wireless listening habits.

The dedicated headphone amplifier is far from an afterthought, delivering comfortable power even for high-impedance studio headphones. The optimized output impedance ensures a linear response with the most demanding multi-driver in-ear monitors.

Technical Specifications

Amplification

• Type: Reference-quality HybridDigital nCore
• Continuous power: 180 W per channel at 8 / 4 Ω
• Instantaneous power: 250 W per channel
• Converter: ESS Sabre 32-bit / 384 kHz jitter-free

Audio Performance

• THD (20 Hz - 20 kHz): < 0.02%
• Signal-to-noise ratio: > 106 dB
• Maximum output current: > 26 A at 1 Ω, 1 ms
• Damping factor: > 150 at 8 Ω, 20 Hz - 6.5 kHz
• Frequency response: ± 0.3 dB (20 Hz - 20 kHz)

Channel Separation

• 90 dB at 1 kHz

• 75 dB at 10 kHz

Input Sensitivity

• Line: 201 mV
• Digital: 10.25%

Connectivity

Inputs

• 1 × HDMI-eARC
• 2 × optical Toslink
• 2 × SPDIF coaxial
• 1 × MM phono input
• 2 × stereo RCA line inputs
• High-definition aptX bidirectional Bluetooth
• 1 × IR input on 3.5 mm mini-jack
• 1 × 12 V trigger input on 3.5 mm mini-jack

Outputs

• Speaker terminals
• 1 × stereo RCA pre-out
• 2 × subwoofer outputs

Physical Characteristics

• Power supply: 100-240 V AC 50/60 Hz
• Dimensions (W × H × D): 435 × 120 × 390 mm
• Weight: 11.2 kg

Included Accessories

• Power cable
• Installation guide
• Infrared remote control