You sometimes experience missing notes while playing, or a note that seems to cut off. While there are other reasons this could happen, a common one is exceeding the available polyphony.
The M3 has 120 voices of polyphony. But that doesn't necessarily mean that 120 notes can be played at the same time! A single note can use more than one voice, as shown below.
A good test for polyphony issues is to take the stereo piano, hold down the damper pedal, and just keep playing notes. Eventually you will run out of polyphony, since even with 120 voices, you have 60 voices with a stereo multisample. And in some programs, that may be using velocity-cross-fading on the oscillators, you could have points of overlap where you are using two voices per oscillator, and if it was a double-oscillator program, you could be using twice that number.
Here's a small chart that illustrates the best to worst case scenarios for Programs:
|Mono/Stereo||Single/Double||Cross-Fade?||Voices Per Note|
|* during the portion of the range where there is overlap|
There are other possibilities, but this gives you an idea. Note that cross-switching the oscillator between two samples does NOT use additional polyphony, since there is no overlap, just a hard switch. But cross-fading the oscillator does, since there will be a portion of the range where two multisounds are sounding at the same time, using up twice as many voices.
Now, note that when you start layering them together in a combi, imagine how quickly 120 voices can get eaten up, not to mention with KARMA and the Drum Track all playing away.