Easier to name the site. it's www.studioax.com
Here's the blurb that made me wonder what digital piano owners thought of it:
Can a soundfont deliver better sounds and more accurate performance than digital grands and sound modules? With the Grand Piano One (GP1) soundfont, the answer is a definitely YES!
Based on a 9-feet Steinway & Sons (model D) and a 8-feet C. Bechstein grand piano, the multi-rate stereo samples of GP1 are digitally recorded, mixed, edited and enhanced. Designed for professionals, Grand Piano One (GP1) delivers studio-quality grand piano sounds from your PC/Mac.