How convincing a digital piano sounds is decided in three places: the sound engine (samples or modeling), the resonances layered on top of the raw recording, and how the sound reaches your ears through speakers or headphones. The polyphony number on the spec sheet is only a reserve figure: 128 voices are enough for most players, and more voices do not make the tone better. Always judge a piano by ear, with the sustain pedal down, through both speakers and headphones.
How a digital piano makes its sound
Sampling: recordings of a real grand
Most digital pianos play back recordings of a concert grand made in a studio with high-quality microphones and stored in the instrument. Each key has several recordings for different playing strengths, called velocity layers. The more layers and the longer and less truncated the recordings, the more smoothly soft and loud notes blend. Modern instruments record every note in stereo, and elaborate systems use several microphone positions.
The weakness: a recording sounds the same every time a key is struck at the same force. Sympathetic string vibration, damper noise and the influence of the case and lid are not automatically part of the recording. That is why manufacturers add these effects as a calculated layer on top of the samples.
Modeling: the tone is calculated
With physical modeling, the note is generated in real time from a mathematical model of string, hammer, soundboard and cabinet. It needs very little storage (the Pianoteq software fits in roughly 50 MB) and allows many adjustments: hammer hardness, strike point, lid position, resonance level, tuning. Early modeled pianos were often called too clean and sterile, especially in the extreme bass and treble. Current models have improved a lot. Neither approach is simply better; what counts is how well a specific instrument is executed and whether you like its character.
Many makers combine both: recorded base tones plus calculated resonances. For sampled and modeled pianos alike, ask which resonances can be adjusted in the menu.
Polyphony: how many voices you actually need
What a voice is
Polyphony is the number of voices the instrument can sound at once. It is not the number of keys you press. Every note occupies a voice for as long as it is audible, including its decay. On top of that:
- Stereo samples: if a note is built from a left and a right recording, it can use more than one voice. How makers count is not standardized.
- Layers: piano plus strings roughly doubles the need per key.
- Sustain pedal: with the pedal down, all notes keep ringing while new ones are added.
- Resonance and effects: simulated string resonance and reverb can claim additional voices.
- Accompaniment and recording: backing rhythms, auto-accompaniment or multitrack recording share the same voice pool.
A worked example
You hold the pedal and play ten four-note chords. That is 40 pressed keys, but the early notes are still ringing. On an instrument that uses two voices per note, 80 voices are in use quickly. With 64 voices, the piano then cuts off the oldest note to make room for the new one (voice stealing). You hear it as bass notes that suddenly stop or inner voices that thin out.
Rules of thumb by use
Common values are 64, 128, 192 and 256 voices. Recommendations vary by source, so treat this as a guideline:
| Use | Sensible |
|---|---|
| Simple pieces, little pedal | 64 is often enough, 128 adds headroom |
| Classical repertoire with lots of pedal | 128 as a good standard |
| Layers, accompaniment, multitrack recording | 192 to 256 |
Player reports agree broadly: people playing simple pieces on 32 voices often never notice a problem, while classical pianists report frequent dropouts at 32, occasional ones at 64 and almost none at 128. Entry-level 64-voice models hit the limit quickly with heavy pedaling, even though they are fine for a beginner piece.
Myth: more voices means better sound
The number says nothing about touch, sample quality, speakers or pedal behavior. A 256-voice piano with thin speakers sounds worse than a 128-voice one with a good amplifier system. Because counting methods differ, a 128-voice piano cannot necessarily play more notes than a 64-voice one. What decides it is a listening test with your own playing.
String resonance, damper resonance and lid position
What happens in a real piano
When you press the sustain pedal, all the dampers lift off the strings. Every string is free to vibrate along, most strongly those harmonically related to the note you play, such as the octave or fifth. It sounds like a light reverb and makes the tone fuller. Struck strings also set their unstruck neighbors vibrating (string resonance). The short string sections behind the bridge vibrate too and add shimmer to the treble (duplex scale). When the dampers touch down and lift off, they also make a faint noise.
What digital pianos do with it
Recorded single notes do not contain this interplay by themselves. Mid-range and higher instruments therefore simulate:
- Damper resonance: sympathetic vibration with the pedal down.
- String resonance: related strings ringing along even without the pedal.
- Damper noise and key-off noise when you release a key.
- Lid position (lid simulation): modeled instruments let you pick a closed, half-open or fully open grand lid, which changes tone color and projection.
Budget units often skip these layers, so pedaled passages sound flatter and drier. On many models you can adjust the amount through the menu or an app (for example Virtual Technician on some Kawai models, Piano Designer on Roland, Smart Pianist on Yamaha). There you can set it to taste or switch it off completely.
How to hear it
Play a bass chord, hold the pedal and let it decay. Then play a single treble note and listen for lower notes quietly ringing along. Switch resonance on and off. If the effect is permanent and exaggerated, the sound turns muddy quickly. Ask also how half pedaling behaves (see hammer action versus basic keyboard for how touch and tone work together).
Speaker systems: watts are not everything
Layout and room sound
Compact pianos often have two small speakers firing upward. In the mid-range, two speakers at knee height firing downward are common, giving more bass and a fuller tone. Higher-end instruments add speakers on top of the key bed for clear mids and highs and use diffusers, horns or waveguides so the sound disperses in the room instead of coming from two points. Some models (for example the Kawai CA-901) pair speakers with a wooden soundboard driven by transducers that radiates in all directions.
Power in watts
Power rises with price class and cabinet size. A rough ladder (as of Oct. 2026):
| Class | Typical |
|---|---|
| Entry-level | 2 x 7 to 8 W |
| Mid-range | 2 x 20 W or 4 x 8 W |
| Upper | 2 x 30 W and more, six speakers |
| Flagship | Three-way system, 45 W or more per channel |
Wattage alone says little. Larger cones, a stable cabinet and a split into highs, mids and lows decide whether the sound stays clear and undistorted. With weak speakers even good samples sound thin and boxy.
Placement
Downward-firing speakers sound different near a wall or on thick carpet. During a trial, check several volumes and, if possible, a second spot in the room. Stage pianos usually have no speakers at all and need an external amplifier, see stage piano versus digital piano.
Headphones: why the sound feels different
Through headphones you hear the recording without a room. Piano sounds come across like a concert recording with artificial reverb, detached from the acoustics around you. Some makers therefore offer headphone optimization that adapts the sound to the ear. One variant is binaural recording: microphones sit at the position of the player's ears, so the tone sounds spatial and seems to come from the instrument. Depending on the maker, it may be available only for certain grand piano sounds rather than all of them.
Practically, almost all digital pianos have two headphone jacks, usually 1/4 inch, so teacher and student can play quietly together. Always test the instrument with headphones and through the speakers, because some models sound much better in one mode than the other. If you mostly play at night, weigh headphone quality above speaker wattage.
Listening checklist
- Start with plain piano sound. Turn off reverb, layers and brilliance controls so you judge the base tone.
- Play softly and loudly. Do the velocity layers blend smoothly or does the tone jump audibly?
- Hold a long bass note and watch the decay. It should fade smoothly, not stop abruptly.
- Play a dense passage with the pedal fully down. Do notes drop out? Do bass and inner voices stay audible?
- Resonance on and off. Is there a difference with pedaled chords and with single notes?
- Speakers at room volume and at high volume. Does anything distort or rattle?
- Put on headphones and check the sound. Are bass and treble balanced?
- Check the pedal: does it respond continuously (half pedaling) or only on/off?
- If you buy online, ask for an unedited video with pedal playing, and for a used piano repeat the same tests at home (see buying a used digital piano).
Price tiers in the US
As a guideline (as of Oct. 2026): portable digital pianos run about $350 to $4,000, console models with cabinet and three pedals about $500 to $5,000, and upright or grand-style instruments about $1,500 to $15,000 and above. Popular entry models sit around $530 to $800: the Yamaha P-145 model (64 voices, 2 x 7 W) costs around $530, the Roland FP-30X (256 voices) around $650 and the Kawai ES120 (192 voices) around $800, with prices varying by retailer and over time. If you want software sounds on a computer instead, read using a digital piano with a VST plugin and DAW, where tone quality comes from the computer rather than the internal amplifier.
Common mistakes
- Comparing polyphony numbers instead of playing the instrument.
- Testing only with headphones in the store, then being disappointed by weak speakers at home.
- Setting resonance to maximum: long pedal passages smear harmonies.
- Holding the pedal down all the time so every resonance runs together. Lift briefly when the harmony changes and press again.
- Treating wattage as a quality rating.
- Buying a stage piano without speakers and forgetting the cost of an amplifier.
