What i meant with usable is the fact when i used Room correction (software) suddenly it looks like a curtain was pulled away an the music became way more transparent. Ok this is probable obvious an was aspect-ed because of my poor acoustics an the room correction flatten out most acoustic anomalies. But then i moved the speakers like 10 a 15 cm away from a wall or table and again i heard a clear change/details (for the better or the worse) an not because i was annalising or expecting it but because I knew the music by hart an love to hear it an noticed the difference. So I was eager to find the best spot not by annalising but pure because of the knowledge of the music I knew so well.
"I'm not sure what the author means about "trying to be objective"
Knowing Richard Vandersteen from previous interviews i think he meant the difference between the left an right side of the brain one is emotional the other one analytic. If you try to be analytical (objective) it could block your emotional side (which implies by him a realaxd state of mind where you could hear more or different) that is probably his assumption. So I don't know if that is an scientifically approach or not.
Ha ha with golf it work for me the other way around if i use my emotional side the ball will go into the ruff if i use my analytical side (a matter of visualization) it blocks my emotional side an the ball go's mostly straight a golf lesson that i learned from a pro 40 years ago who also advised me to read the "Inner Game Of Golf" by Gallwey. My Handicap went down from 23 to 14. Could work for listening to decent gear to but than the other way around.