The ML2.2 is the latest iteration of the classic amp, making improvements over the previous model.  The ML2.2  ups the ante from the ML2.1 thanks to a completely redesigned input stage that's based on that of the ML3 Signature amplifier.

It also boasts a new power transformer, five filter chokes as compared to the two in the company's previous offering and a higher quality PC board.  LAMM also introduced a few convenience features, like easier access to fuses and the option to turn the amp on and off remotely.