Building on the general explanation of what polyphony is, here's a more concrete look at how much is actually enough for different situations.
Rough guidance by use case
- Simple solo piano practice, beginner/intermediate level: lower-end polyphony specs are rarely a practical limitation, since simple pieces with moderate pedal use don't typically approach the ceiling.
- Advanced classical repertoire with heavy sustain pedal use: dense, highly pedaled passages can consume polyphony quickly as previous notes' decay tails overlap with new ones - higher polyphony headroom avoids audible cutoffs.
- Layering and splitting sounds, or using accompaniment/backing features: each additional layered sound roughly multiplies the voices used per note, so headroom matters more here than for a single piano sound.
The practical test
Rather than comparing numbers alone, playing a demanding piece with full sustain pedal use on the actual instrument (or a very similar model) is the most reliable way to hear whether polyphony is actually a limitation for your playing - abrupt, unnatural cutoffs during dense passages are the tell-tale symptom of running out.
