Atma-Sphere M-60 Mk 3.3

For years now the M-60 in its various forms has been the subject of the Soundstage!.com Hall of Fame Award, The Absolute Sound Golden Ear Award and Editor's Choice, with numerous accolades in the press and on the web. 

The M-60 Mk. III.2 continues that tradition with classic styling and its award-winning State-of-the-Art performance. The M-60 Mk. III.2 gives you the features and precision performance of our larger models in a beautiful, 60-watt package. The amp operates class A and is unconditionally stable with proven reliability. The power tubes are inexpensive, readily available and do not require any matching. Now sporting a classic open chassis construction, the M-60 Mk. III.2 sets the bar for hi-end amplifier performance.

Design features of the M-60 Mk. III.2 include:

  • Balanced Differential Design®
  • Class-A operation
  • Patented Circlotronic® direct-coupled (OTL) output stage
  • Automatic bias - no adjustment needed
  • Built in VU meter for tube and output monitoring
  • Easily monostrapped for greatly increased power
  • Standby switch for long output tube life
  • Uses only one gain stage for supreme 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: 60 watts per channel into 8 Ω load, 45 watts per channel into 4 Ω load, 80 watts per channel into 16 Ω load.


      • Input Impedance: 100KΩ single-ended, 200KΩ balanced.
      • Output Impedance: 4.1 Ω

      Input: 2.83V sensitivity (RCA and XLR true balanced input).

      Tube Complement (per channel): 8 x 6AS7G output tube, 4 x 6SN7 driver tube.

      Gain: 23dB (for 8 Ω).

      Power Bandwidth: 2Hz-75KHz within ½ dB.

      Frequency Response (1 watt, open loop):

      • 20 Hz squarewave Tilt; unmeasureable.
      • 1Hz-200KHz within 3 dB.


      • Total Harmonic Distortion (THD) typically under 5%.
      • Intermodulation (IM) distortion typically under .04% at full power.
      • Phase shift less than 1° @ 20KHz.

      Output Section Risetime: 600 V/µs.

      Feedback: 1 dB.

      Power Consumption (per channel): 300 watts.

      Power Supply Storage (per channel): 140 Joules.

      Dimensions (per chassis): 13" deep x 17" wide x 8" tall (33 x 43 x 20 cm).

      Weight (per chassis): 30 lbs (13.6 kg) without tubes.

      Warranty: 3 year general coverage, 1 year for output tubes.



      Optional Features

      • V-Cap Copper Foil Teflon® coupling caps: $600
      • Power supply boost: $450
      • Caddock® resistor upgrade: $1270
      • Custom volume control: $1200