I have known Koh Joo Ann since the 1980s when the Singapore Cultural Foundation awarded him a financial grant to study piano in Germany. The last few times I visited Vienna where he teaches piano, Joo Ann and his friend Dr Wilhelm Klocker brought me and my companion Dr Paul Tan on historical walks of Vienna and day trips by train to nearby cities like Melk and Slovenia.
When Joo Ann found himself stuck in Singapore due to COVID, I reciprocated by taking him to his childhood haunts. One of his targets was Haw Par Villa where I saw the funnier side of him, an actor to boot. I am really glad we kept this theme park in spite of the many sites we have lost.
My Arts Bucket : Life is an Endless Stream of Goosebump Moments! 
Thank you for posting about Prof Joo Ann Koh!
I am Hiro who lives in Tokyo and was taking piano lessons in Wien between 1998 and 2017.
He is an excellent piano techer!
please send my regards to Prof. Koh!