Simple question, but I have not done this before. I want to connect an older stereo cassette deck to my iMac. I connected the line out from the deck to the audio input jack on the iMac. With the tape playing, I can "see" the audio signal in Preferences > Sound > Input. It stops and starts when I pause and play the tape, so it would seem the signal is there ok. However I have no sound from the speakers. Audio from browsers, Audirvana etc. are fine from the speakers. Am I doing this right?
I think the mac might be confusing the device as a mic. I'd look into seeing if you could 'record' the input from the device, and then play it back from that recording to verify.
I think you are right. With out software out output the input, you would be able to hear it. Exactly. To the OP: I can't remember the name of the software that I used to copy my vinyl to mp3, but it is in the Mac App Store. There was a couple of when I did a search, and I think I picked a free to try one, then purchased it after seeing the results. I am sure there are plenty in the store, and probably some free ones for the basic payback that you are looking to do. If you want to use Apple's software, I think Garage Band would work for this I think. At a minimum you are make a copy of the cassette, and play it back later.