With 5 volts into a 4 ohm load, IMD was 0.0401%, using the SMPTE/DIN standardized test.

At 20 volts output into 4 ohms, IMD was 0.508%.

At 5 kHz and 6 kHz, 20 volts into 8 ohms, the 1 kHz difference peak was at - 63 dB from the fundamentals.

At 4 ohms, the difference peak between 5 kHz and 6 kHz was at - 88 dB.

At 10 kHz and 11 kHz, 8 ohms, the difference peak at 1 kHz was at - 64 dB.

At 4 ohms, the difference peak was at - 90 dB.

Below is a graph of THD+N vs. Frequency, using a 5 volt output into 8 ohms, 4 ohms, or no load. You can see how constant the distortion is throughout the audible range.

At 20 volts output, THD+N is still rather constant in the audible range.

THD+N vs. Power Output shows that distortion at very low output is at about 0.1% or lower, then declines to its lowest values from 4 to 12 watts, depending on impedance, then rises to 1% (defined here as the clipping point) at 260 watts with an 8 ohm load, and 313 watts at 4 ohms. For these tests, I used the upper toggle position for the 4 ohm measurement, and the lower toggle position for the 8 ohm measurement.

The measured frequency response was 10 Hz - 180 kHz, + 0, - 3 dB.

Conclusions

I don't know if the Lamm M2.2 is the best power amplifier in the world, because I have not heard all the power amplifiers out there. But, I can say that it is one of the best audio products I have ever heard, period. It is priced like a Maserati, has conservative looks as does a Maserati, and performs at a level like a Maserati. I simply can't imagine anything sounding better than this.
 

- John E. Johnson, Jr. -