You have a record collection this big and all you do and think about every day is records and music. So just how closely have you been listening? Can you tell a note out of place in a chord? Lots of testees are surprised and horrified to discover they can’t. It took me a few tries, so you can get better.
I really didn’t think it was very hard! It’s odd to imagine this being difficult (and I’m known to have poor musical ears, despite being a musician).