Well, .msv appears be from a Sony voice recorder. From what I can find, the software that come with the voice recorder is for Windows only. You going to need to use a Windows computer to convert this sound file to a WAV file. Then Quicktime can import the WAV. Sorry if this isn't the answer you wanted to hear. Sony chose the go the Windows route only.
You can how ever record from the audio out from the recorder to the audio in of your mac.