Input:
Proprietary electronically balanced discrete enhanced class A circuitry, non-polarized, floating, non- inverting or inverting mode. Optimal performance with either balanced or unbalanced (single-ended) sources. Unbalanced sources are automatically balanced right at the input of the FM 411.

Input Sensitivity:
1,6 V RMS for full output

Input Impedance:
At all level settings from balanced and unbalanced sources: 40 kOhms

Interference Rejection:
Better than 80 dB at 50 Hz, even better at other frequencies.

Load Impedance:
No minimum impedance. The amplifier is designed for 1 Ohm to 10'000 Ohm systems. It can drive any speaker impedance (even below 1 Ohm) with dynamic (music) signals without any limiting, compression or other negative effects on the audio signal. Despite this, the amplifier is fully protected against short circuits, open circuits and all other adverse conditions via a unique onboard computer that continuously surveys all important parameters.