Raidho XT-3 Demo Used for Sale

Atma-Sphere MA-2 Rev 3.3 Mono Tube Amps (Consignment)

Original Retail: $42,000
Specially Priced At: $13,000

Atma-Sphere MA-2 MK 3.3 Mono Tube Amps

Customer consignment sale : Atma-Sphere MA-2 Mk 3.3 mono block tube amplifiers in excellent condition. These have all the upgrades.  One owner, bought used from Atma-Sphere in 2008. Approximately 2 years left on manufacturer’s warranty. 

The MA-2 is noted for its superior performance on Sound Lab, Wilson Audio, JM Labs, Magnaplanar and Avalon loudspeakers. These are speakers that need an amplifier capable of serious power. An amplifier that can fully utilize the full bass frequency range of the speaker with the proper control and impact, while simultaneously retaining detail, delicacy, and speed. This is an unusual combination but this is what sets Atma-Sphere apart from the competition.

ow the Mk. 3.3 boasts an improved gain stage with even wider bandwidth and greater transparency than ever before. They added switchable feedback and automatic tube biasing to round out the package. Yet it remains smooth, detailed, and tuneful with a speed that belies such a large tube amplifier. Unlike many other amplifiers, it will stand up to constant playback without any noticeable artifact. And the improvements the MA-2 offers will be obvious on any system within seconds of powering it up; it sounds that good.


  • Balanced Differential Design®
  • Class-A operation
  • Patented Circlotronic® direct-coupled (OTL) output stage
  • Automatic bias, so no adjustment is needed
  • Built in VU meter for tube and output monitoring
  • Copper foil V-Cap Teflon coupling caps
  • Easily monostrapped for greatly increased power
  • Standby switch for long output tube life
  • Dual AC power circuits for each chassis
  • Uses only one gain stage for simplicity and clarity of sound
  • Proprietary precision components used throughout
  • Low-noise “star” grounding topology
  • Fully hand-wired point-to-point electronics – no circuit boards!
  • Stable with all input and load conditions

Exclusively uses Octal-Triode based vacuum tubes





Output power

220 watts per channel into a 4, 8, or 16 Ω load before clipping


Selectable up to 600 Ω
2.8 V sensitivity
RCA and XLR true balanced input

Tube complement

( per channel ) 20 x 6AS7G output tube
6 x 6SN7 driver tube


26dB ( for 8 Ω )

Power Bandwidth

2Hz-150KHz within 1/2 dB

Frequency response

( 1 watt, open loop ) 20 Hz squarewave Tilt; unmeasureable
1Hz-200KHz within 3 dB



Total Harmonic Distortion ( THD ) typically 0.4% at full power
Intermodulation ( IM ) distortion typically under .04% at full power
Phase shift less than 1 degree @ 20KHz



Input Impedance: 100 KΩ single-ended, 200 KΩ balanced – selectable to 600 Ω
Output Impedance: ~1.75 Ω ( open loop )


Output section risetime

600 V/µs



2 dB


Power consumption

800 watts/channel


Power Supply Current

80 Amps/channel


Power Supply storage

( per channel ) 1200 Joules in output section, 100 Joules in Driver supply



( per chassis ) 28″ deep x 17″ wide x 10″ tall ( 71 x 43 x 25 cm )



( per chassis, without tubes ) 103 lbs ( 46.7 kg )



Three year general coverage
One year for output tubes