Tape Loop Testing On A Preamp?

One simple way to check out a tape loop is to take one set of IC's and connect them to the tape in and tape out creating a simple loop. Then play a CD or whatever and hit the tape monitor switch. If it's working you will not hear anything - the music will keep on playing. If it goes quiet then most probably the switch is dead. Just a WAG.

"If it's working you will not hear anything - the music will keep on playing." Those are opposites, New. If the loop is working, Licorice will indeed hear something, since the music will continue playing.
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Jefferybehr, You are right. What can I say? I should have said 'if it is working you will not hear anything but the music playing'. OK?

I set up the loop between Tape 1 Play, and Record. I put on a source. Then, I selected Tape 1 record, and I could still hear music. Does that mean it is working? This preamp is confusing.

Yes, it means the tape loop is working. You are doing something else perhaps?

What was connected to the 'tape in' RCAs when you had problems?
What was connected to the 'tape output' RCAs when you had your problem?