There are a number of iPhone applications that allow adjustable recording quality. I would just use one of those to record and then email the resulting file to Evernote. Its quite simple to do. I just tested it with the VR+, which is the recording app I've used the last couple of years. I chose to record a high quality mp3 from a lecture I attended. It showed up in Evernote properly and looks and sounds great. If you really wanted super high quality, you could use an external microphone connected to the iPhone's earphone\microphone jack to bring in seriously high quality audio by adding an external microphone or connecting directly to an audio source.