AM400 Signature

During the development of the power amplifier AM400 Signature, the attention to detail led us to take into account all the parameters, to compare and listen to each component. The power stages have 8 MOS-FET transistors per channel which provide considerable energy, perfectly controlled thanks to carefully designed audio stages. The connecting cables between the motherboard and the loudspeaker outputs are made of pure copper, deoxygenated, silver plated with Teflon insulation. One of the best French manufacturers of audio cables makes these cables on demand. Similarly, filter capacitors, with low series resistance, are made to specifications by a leading specialist. 

  • 10 mm brushed aluminium front.
  • 2 mm steel frame.
  • Linear power supplies based on toroidal transformers.
  • Symmetrical stages with discrete components.
  • XLR balanced inputs.
  • RCA inputs (selectable on the rear panel).
  • Mono block bridgeable amplifier (switch facing the rear).
  • Integral dual mono structure.
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Audio inputs
1 Stereo line input.
1 Stereo XLR input.
1 Trigger input 12V.

Audio outputs
1 Stereo line output.
1 Stereo speaker output.
Input type selector:
– Line: button up.
– XLR: button pressed.

1 Mono bridge switch.

The gold-plated loudspeaker output plugs have been selected for their ability to transmit without alteration all the energy and the micro-details of the electrical signal. The polypropylene film structure link capacitors have been selected for listening in the high-end series of the largest manufacturers. In bridged mono mode, the energy gain is colossal: this operation is suitable for all systems where high power is required. The differential structure diagram makes it possible to carry out this transformation without altering the nuances of the musicality, the gain in “sound material” makes listening even more realistic.


Power Wrms/8Ω: 160 W
Power Wrms/4Ω: 300 W
Power in bridged mono/8Ω mode: 600 W
Power supply: 1050 VA
Total of capacitors: 111 300 μF
Input impedance: 220 kΩ
Sensitivity: 1,7 V
Signal/Noise ratio: 100 dB
Distortion at 1 kHz: 0,005%
Bandwidth: 5 Hz – 200 kHz
Rising time: 1,5 μs
Dimensions (mm): 440×370×130
Weight: 19 Kg


“An idea circulates in the audiophile world, that the music seems to flow a little more slowly when it is reproduced by Hi-end electronics. This thesis applies quite well to the Atoll couple, of which it should be noted that the ensemble has been evaluated in all symmetry from the source to the amp. This point is crucial in the perspective of awarding it a Hi-end patent. The other salient aspect, from the first bars, is the size of the sound stage that goes far beyond the frame of the speakers: in front, behind, on the sides, but also above.”

Diapason magazine, no. 688, March 2020

The AM400 Signature model is available in black or natural aluminium:

Black anodized brushed aluminum finish.
Silver anodized brushed aluminum finish.