[Cykomiko]

The Nuprime website states that "STA-9X switches at a frequency of 750kHz".



In the manual of the unit that I recently purchased however it is stated that "STA-9X switches at a frequency of 600kHz".



Which one of the two statements above is correct?

[rustydoglim]

Hmm, I have to check.  Sometimes the spec changed or an error was corrected but I wasn't informed to update the website.

[rustydoglim]

I confirmed with R&D that the website is correct, STA-9X switches at 750KHz. 
Please remember that up to a certain point, switching freq at 750K doesn't mean it will sound better than another Nuprime amp that switches at 600K.  In general, all else equal, switching at higher freq resulted in smoother and more detailed sound, which is noticeable between 700K and 300K.
Our best amp, Evolution Two, switches at 650KHz because the design requires it (I was told by the chief engineer)

[Cykomiko]

Many thanks for the clarification Rusty!