In pianos it's not about bass, but about the amount of air mass that is being moved. Acoustic piano moves everything. Now, be Kawai CA701 and you have two tiny 13cm speakers... I pointed it few times to Kawai James that this is not enough to replacing piano sound, and his answer was that engineers made this decision so it is enough.
Yamaha has 16cm drivers and that is like 50% step up in speaker area, if not more.
Roland has two 32cm or s9mething like that speakers in their top pianos, and believe.me, it makes a difference. When playing on Roland you can feel that the whole air around youbis vibrating, something that is not achievable in K and Y. You just can't break physics here and the fact that those tine 13cm Kawai drivers can play from 50Hz brings nothing to the table, as the point in the top pianos is different than "what smaller diameter driver will be good enough for piano frequencies"