Halogen to LED undercabinet lighting - easy switch?

Hello, about 15 years ago I had a total kitchen remodel done. Halogen puck lights were put in under my cabinets (surface-mounted) by a reputable contractor. 6 in total, hardwired to a single switch. The lights say 12vac 20 watt max on them. I'm assuming there is a transformer somewhere, although i can't find in. Not in basement, not in cabinets, not on top of cabinets. Possibly in the wall? anyways, I'd like to switch the very hot halogen pucks out for LED pucks. Is that an easy switch? can i just switch out the pucks if I can find 12V LED pucks? Thank you in advance for any advice you can give!