It seems that NAudio only contains WinForms visualizers. Would you (or anyone else) be interested in collaboratng on a collection of WPF visualizers built on WPF?
NAudio does contain some WPF visualisation. Have a look at the WPFDemo project in the solution. Also the VoiceRecorder project on codeplex uses NAudio and does WPF visualisation.
As for ASIO support, I'm afraid its not ready for the prime time yet. Needs a lot more debugging before it will work with all cards. (does seem to work with ASIO4All though). I did integrate ASIO.NET with NAudio at one point in the past & it worked quite well, although we have moved to a fully managed implementation since.
Finally, you need to know that you will never get really low latencies with .NET due to the garbage collector. A better approach would be to have the audio mixing engine unmanaged and just do the GUI in .NET.