Precision timing in .NET

If you don't mind P/Invoke, you can use QueryPerformanceCounter: http://www.eggheadcafe.com/articles/20021111.asp

You could also use the native streaming MIDI API. I don't think its in NAudio but you could look at the C# Midi Toolkit to see if that one supports it. Otherwise you have two examples of how to do native MIDI API P/Invoke and can roll your own...