I don't remember ever hearing the 2.3 before, but I own the Superone and used to work at a shop that carried the entire NHT line. Although every model seem to have an incremental change/improvement in design as you move up (larger bass driver etc.), the 3.3 is an entirely different animal from the guys below it in my opinion, and I am speaking only of the newer version with aluminum tweeter.
The main difference that mattered to me is transparency. The 3.3 sounds completely "boxless" with tons more detail.
The main difference that mattered to me is transparency. The 3.3 sounds completely "boxless" with tons more detail.