Good timing btw, I just got back. If anyone wanted to know if I was around, your post would catch me hook, line and sinker: Feynman on Audio??? Yes thanks ..

This product looks like it would do the job, although I've never used it. It's just what I found through Google, but it looks good. Maybe read the FAQ and decide if you can do it yourself ..

If I had tapes for mp3 conversion, I'd pipe them from the cassette player into the Mac (with sound input changed to 'line in', of course). I'd record them using Pro Tools Free, with which I have some experience. I'd be careful with recording levels and maybe stick in a limiter or compressor on the output master, depending on the quality of the original tape. I'd then bounce the whole session down to disk in .aiff format, and convert to mp3 using iTunes.

This is quite time-consuming as it all is done real-time: X minutes to feed an X-minute long tape recording into ProTools, and then another X minutes to bounce the session down to aiff format. That's why I hardly ever do it. (I've only done it with a 25 year old Monty Python tape, to save the audio before the tape vanished.)

But it would be worth it with Feynman. I would be happy to do it for you and send you the mp3s on CD or make them available on my website - both at my expense. The problem would be getting the tapes to me, and then me getting them back to you. If you can figure out a way to do that, let me know. Now would be a good time, as I plan a much longer trip (20+ hours rail travel) at the end of the year, and then, if one of two applications are successful, I will be busy early next year moving interstate.