Loop back works! iMac trick.

[dave2010]

If you push one end of an optical fibre cable into the headphone socket and the other end into the microphone socket of a newish iMac, and then run software such as Audacity on the machine, it's possible to pick up anything which comes out of the headphone socket.

Is this useful? I couldn't comment, but it does work!

[Werner Berghofer]

Is this useful?

No, I don’t think it is, but I’m really glad to see that discovering this feature makes you happy so much ;-)

Werner.

[Vincent Kars]

Loopback is convenient for a null-test.
Is there a difference at bit level between FLAC – WAV, Player A or Player B, etc.

Play A and record it
Play B and record it
Time align the 2 recordings and subtract them.
If they don’t nullify, they differ
A nice example: http://www.computeraudiophile.com/content/first-test-and-some-food-audio-thought

[dave2010]

Actually it can be useful. The alternative is to find software which will record any output on the iMac. I believe such exists, though I'm not sure if it's free. Audacity is free. Also it may be possible to configure tools such as Audacity to pick up the audio streams, but I don't know how to do it, so under these circumstances the loop back solution is neat enough, and cheap if you have the optical cables to hand.

There have been other methods in the past, but some streams have become increasingly hard to pick up, for various reasons.

[Werner Berghofer]

Dave,


The alternative is to find software which will record any output on the iMac.

I can highly recommend Audio Hijack Pro (http://www.rogueamoeba.com/audiohijackpro/). It’s not free, but in my opinion the price of £ 20.– | US$ 32.– is very fair.

Werner.