For ASIO (ASIO4All needed, see quickstart guide), check the buffer size. Click the ASIO icon in the toolbar. 
The best setting for most systems is 1024. After changing the setting in ASIO4All, the application will 
need to be re-started.

Remember that the Low Pass filter in the Simulator does cut out harmonics in the higher notes if set to 
2000Hz. It should be set to 4000Hz or None to hear D#5 and F#5 correctly.