“After 8 years I still cannot play as expressively on my Kurzweil K2000 as on my Yamaha upright (not surprising). I’d much prefer to record a cassette tape of my piano, and using an outboard box or possibly software, convert the audio file to a MIDI file. I don’t care about pitch accuracy (that’s easy to edit in MIDI), but I do care about the “feel” (exact rhythmic conversion, and possibly dynamics), which are much harder to “fix”. Any products on the market?”
There have been a variety of products over the years that claim to do this sort of thing, but almost all of them have been monophonic (as opposed to polyphonic, not stereophonic). There’s never been any effective commercially available solution that works for things as complex as piano parts (unless only one note at a time is being played). The problem is that once two or more notes occur at the same time a new sound has been synthesized and it becomes extremely difficult for software to know what the original notes were. Our brains are uniquely powerful and well trained in this regard.
The closest hardware that would accomplish what you are trying to do would be Yamaha’s Disklavier MIDI system that can be built right in to their pianos. We use one in our studio and it works very well. This system is very cool because it also lets you play back the acoustic piano from MIDI. Sort of a Player Piano concept. We can bring an entire band into the studio and the pianist can sit right in the room with them and record live. We don’t even have to mic the piano. We just record the MIDI performance. Later, we can move the piano into the middle of the room, mic it up properly, and play back the (edited) MIDI performance and make a “perfect” recording of the piano. One service our studio offers is to take MIDI files from any source and produce a real piano recording from them.