M-60 Mk. 3.3
monoblock music amplifier 
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. 3.3 continues that tradition with classic styling and its award-winning state-of-the-art performance. The M-60 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 reliability proven over many years. The power tubes are inexpensive, readily available and do not require any matching. Sporting a classic, open-chassis construction, the M-60 Mk. 3.3 sets the bar for hi-end amplifier performance.
  • Balanced Differential Design®
  • Class-A2 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 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

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: 100 KΩ single-ended, 200 KΩ balanced
Output Impedance: ~4.1 Ω


3 V sensitivity ( for full output )
RCA and XLR true balanced input

Tube complement

( per channel ) 8 x 6AS7G output tube
4 x 6SN7 driver tube


20dB ( 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 1%
Intermodulation ( IM ) distortion typically under .04% at full power
Phase shift less than 1° @ 20KHz

Output section risetime

600 V/µs


1 dB

Power consumption

( per channel ) 300 watts

Power Supply storage

( per channel ) 140 Joules


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


( per chassis, without tubes ) 30 lbs ( 13.6 kg )


Three year general coverage
One year for output tubes
For all support requests, or any questions about your Atma-Sphere product, contact us directly at (651) 690-2246 or send us an email.

Optional Features

V-Cap Copper Foil Teflon® coupling caps
Power supply boost
Caddock® resistor package
Custom volume control

Meter Panel finish options

Gray Hammertone
Brushed anodized black
Brushed anodized silver
Brushed anodized gold
Custom finishes available


Jumper plugs for high efficiency speakers
      Replaces tube in the voltage amplifier section of Atma-Sphere
      power amplifiers, thus reducing gain for high efficiency speakers.
      Recommended when efficiency of speaker is over 100.


Balanced Interconnects
Balanced phono cables
      1 meter, DIN to XLR or RCA with ground post to XLR


Contact your local dealer for pricing information.
Or, call (651) 690-2246 or email us with any questions.
The M-60 kit is back!

We are now offering an M-60 in kit form based on the Mk. 3.2 revision. It has the same features and specifications as the stock factory-built version and is available with all of the same options.

You get all of the same factory components you need to build a stereo pair of M-60 Mk 3.2 amplifiers including two powder-coated chassis, lengths of our custom wire, and a full set of driver and power tubes.

Most importantly, it comes with thorough pictoral doctumentation and up to two hours of telephone consult time to help you get your new M-60 up and running smoothly.


Contact your local dealer for pricing information.
Or, call (651) 690-2246 or email us with any questions.