I have watched quite a few masterclasses, where it has been suggested you try and make the piano imitate another instrument - apparently because the piano is a percussion instrument it has its limitations wrt melodic timbre.
To be honest I really hate this idea. The piano can NEVER sound like a violin, or a cello or an oboe, whatever inner desire you might have. To me this is like an insult to the instrument I love. I think the piano sound is the most beautiful of all. I love the way the harmonics are always so alive, and the way it isn't sustaining like a violin, this is what gives the piano it's own unique character. It is that character and beauty I want to find in every note. Yes, the piano has to sing sometimes, but I am part of the sound and I sing inside - I don't want to emulate the human voice though - which of course is impossible for anything other than the human voice.
I am sure a cellist is hardly ever told to try and make it sound like a piano!
I sometimes why Barenboim bothers to play the piano at all - he insults it often enough. If I had been good enough to participate in one of his masterclasses - I think an argument might ensue!