But the truth is, most people, if blindfolded, cannot distinguish between an acoustic and digital sound.
Qualification: IF Recorded you are right ... if LIVE you are wrong... that is: ANYONE, even a complete novice, can immediately tell the difference between playing a REAL piano (however bad) and a FAKE (keyboard with samples) piano
A really cleverly mixed recording of a sampled piano CAN indeed be difficult if impossible to distinguish from a recording of a real live piano performance.
But even recorded "sampled" or "fake" piano CAN be spotted in many cases, at least in the context of classical piano recordings for the following 2 reasons...
A. sampled or "fake" pianos are rarely recorded at a distance, or in a concert hall setting
, and that type of recording is the hallmark of virtually ALL classical piano recordings. There is no market for that kind of sound in the world of sampled pianos. JAZZ or POP is the
market, and that means CLOSE MIC recording techniques are used for ALL modern piano samples.
As a result, even great (and expensive) sampled piano recordings (like the online demos of Vienna Imperial or East West Steinway or Garritan Steinway--yours truly did one for the latter) employ CLOSE mic sampling, for the most part. Even their "room mic settings" sound to mee pretty much like a "close mic" type of recording, at least, relative to what one might typically encounter in a standard classical piano recording hall.
So the sound of the expensive, high end sampled pianos is just not the same as the sound one encounters in a classical piano recording. Yes, there are exceptions...in the sense that SOME (very, very, very few classical recordings) are close miked: Gould insisted on close miking, and you can hear it in all his recordings!!!
Alternatively, there are some old piano samples out there that actually experimented with sampling "in a hall", ie making piano samples that were based on quite reverberent contexts. Needless to say, these samples didn't sell; because the vast majority of users wanted "close mic" sampling, ie, samples that would "cut into a mix" or that could be used in live pop performance settings... ie playing a fake piano LIVE!!! (So the "hall" is already there, so to speak; that last thing you want is a reverberent sound.)
B. Good speakers (really good, and accurate) are quite revelatory of the sampled piano sound, especially given the above. But on many middle range stereos, and certainly on computer speakers, it may not be easy to tell the difference between sampled and real.
The entire debate is being rendered moot. Now relatively inexpensive (or so I'm told) midi add-ons for REAL pianos mean that you can essentially have the best of both worlds: a totally live piano sound based on a midi file.
As far as the best portable fake piano for practising is concerned, none of them sound or feel remotely like the real thing from the perspective of the person actually playing; but some sound like recordings of pianos, in a way. (so you have to do a kind of mental trick when you are practising on one.) That being the case, the most important factor is TOUCH, and the general consensus is that KAWAI makes the most realistic touch. There are, I think, two classes of Kawai keyboard, and both are supposed to be pretty close to a real piano touch.