Can iTunes Match recognize songs recorded from analog sources (line-in, cassette, vinyl LP, or FM radio), or only digitally-extracted CD audio?
Analog Source over Line-In &rarr; iTunes Match:&nbsp; It works!&nbsp; Kind of.

I just ran my experiment.  While I don't have a cassette player handy, I did have the means to make a reasonably good quality analog recording to try with iTunes Match, as follows:


I used this old CD player:

And this excellent CD:

I plugged the CD player into my Windows* PC's blue audio input (line in) with this cable:

I recorded the entire CD using EAC's "Record WAV" feature. Then, I split up the resulting single, large WAV file into individual WAV files (using EAC's "Process WAV" menu item.)  I judged the track boundaries by eye/ear, and I ended up within a second or two of the actual track lengths reported elsewhere.
I compressed the WAVs into MP3 using EAC w/LAME.
I renamed and copied the resulting MP3 files to my Mac.
I added the MP3s to iTunes, and then added them to iCloud.  After a few minutes, iTunes Match finished doing its thing, and 10 of 11 tracks were Matched.  Proof:



Summary

It doesn't appear that a strictly digital-sourced (i.e. ripped) MP3 input is required for iTunes Match to succeed (somewhat) at matching.  However, I did make sure line levels were appropriate during recording to avoid clipping, and though my recording was analog, the source is high quality.

What I still don't know is if iTunes Match would work with audio cassette, LP, or FM-sourced audio.  Does anybody care to run a follow-up experiment? :-)



* (my apologies for using Windows for the recording part of this experiment. I'm not yet familiar with audio recording/editing on the Mac.)