Nagra AMP II-S

Nagra AMP II-S

The Nagra AMP II-S is a Swiss-built Class AB stereo power amplifier rated at 120W rms per channel into 8 ohms, with 10W of Class A operation. It succeeds the Classic AMP introduced in 2015 and is designed as a natural partner to the PREAMP II-S. Nagra builds it around a new linear power supply, a single pair of MOSFET transistors per channel, and a revised mechanical and thermal design.

Where It Fits in the Nagra Line

The AMP II-S expands Nagra's new Series II, which began with the PREAMP II-S. Within the Nagra range, it sits between the Classic line and the HD line. It replaces the Classic AMP, keeps the qualities that made that amplifier successful (natural tonal balance, effortless dynamics, and power combined with refinement), and draws on what Nagra's engineers learned developing the HD and Reference electronics over the last decade.

That lineage shows up directly in the hardware. The AMP II-S uses a new input board derived from the Reference AMP.

From Classic AMP to AMP II-S

For listeners who know the Classic AMP, Nagra describes the AMP II-S as a significant evolution of the same musical character. The company says its engineers revisited every critical area, from the power supply and input stage to PCB layout, thermal management, and mechanical construction. According to Nagra, the changes bring greater transparency and clarity, more precise spatial definition, increased dynamic authority with a sense of control, and a deeper, more generous bass foundation with greater definition.

Power Supply

The core of the amplifier is a new linear power supply architecture that provides greater energy reserves and increased voltage headroom. It uses a custom 800 VA potted transformer, chosen for its power reserves and quiet mechanical operation. The transformer is suspended to absorb 99% of vibrations between 50 and 100 Hz, which prevents audible hum. Rail voltage is increased for more headroom and better transient capability.

Output Stage and Signal Path

Each channel uses a single pair of MOSFET transistors, an approach Nagra chose for transparency. The amplifier operates in Class AB, with 10W of Class A for sound purity. The new input board improves left and right channel separation for more precise imaging, and the path from the input stage to the power amplifier is hand-wired. New internal cabling and an optimized, rerouted PCB layout complete the signal path changes.

Thermal and Mechanical Design

A massive CNC-machined heatsink minimizes unwanted vibration and provides high thermal inertia, which keeps operation stable. The controls and front panel are optically isolated from the circuitry to keep noise low. The amplifier rests on Nagra spikes, supplied with new spike cups.