Atma-Sphere Class D

Class D monoblocks, 2 x 100 Watts

Our Class D project has been in the works since 2017. Our goal was to expand on the positive attributes of our existing amplifiers, which have been getting great reviews and awards in the high end press for the last 30 years. So we felt we were in a good position to know if the goal was achieved. The result is a solid state amp that has all the smoothness in the mids and highs that you expect from an excellent tube amp but with considerably lower distortion, output impedance and obviously higher efficiency. Like our other amps, this one has a very nice first watt!

The Class D is a monoblock design based on GaNFET output devices and accepts both single-ended and balanced inputs. The circuit is entirely our own design and manufacture- it does not use anyone else’s modules. The power supply employs a toroidal power transformer and has over-current protection to keep the amplifier safe in case of a short at the speaker terminals.


– Single-ended and True Balanced input
– GaNFET output transistors
– rugged chassis
– Monoblock
– No adjustments needed

– Exclusive Atma-Sphere class D module
– Precision components used throughout
– Low-noise even on horn speakers
– Over-current protected
– Stable with all input and load conditions
– Classic Wrinkletex™ finish
– Three-year general coverage warranty



Output power
100 watts per channel into 8 Ω
200 watts per channel into 4 Ω

Input Impedance
100 KΩ balanced/single-ended

Output Impedance:
~0.010 Ω

2.15 Vrms for full output


Power Bandwidth

Frequency response

Total Harmonic Distortion less than 0.1% at full power.
IM distortion less than .04% at full power.

35 dB

Power consumption
5 watts at idle (per channel)

Dimensions & Weight
13″ deep x 11″ wide x 3″ high (33 x 28 x 8 cm) per chassis
14 lbs (6.35 kg), per chassis

Three year general coverage