One of the most significant developments in player piano history was the introduction of the reproducing piano. Whereas the foot-impelled player piano requires a certain degree of skill on the part of the operator to impart musical expression and phrasing, the reproducing piano is designed to achieve this without any manual intervention. Its function is to faithfully reproduce the music of human pianists, who recorded their work for the music roll medium. For the listener, a well-adjusted instrument should create an impression that the original recording artist is present in the room, playing the piano himself.

Mechanically, the reproducing piano is akin to any ordinary player piano, except that the foot operated bellows are displaced by an electric suction pump, and a sophisticated expression control mechanism is incorporated. It functions by regulating the level of suction with which the note pneumatics are operated, consequently varying the force with which they collapse and the intensity of the notes they play. The rolls are coded with the required expression information, by means of additional marginal perforations.

The first instrument of this type was introduced just after the start of the twentieth century, by the Welte company of Germany. The so-called 'Keyless Red Welte' dispensed with the foot pedals and hand controls in favour of electric operation and as its name suggests, possessed no keyboard. Welte also introduced a cabinet-style external player, for use in combination with any ordinary piano and later installed their system within fine quality grand pianos, most notably the Steinway.

Several other companies, predominantly in the USA, subsequently introduced their own design of reproducing systems, the most successful of which were known as Ampico, Duo-Art and Welte-Mignon (Licensee). All of these systems were invariably fitted to fine quality pianos and were considerably more expensive than their pedal-powered counterparts.

The musical capabilities of the reproducing piano attracted great interest from eminent pianists of the player piano era. Understandably, many considered the music roll to be an excellent alternative to the phonograph, which at the time could provide little more than low fidelity sound.

Ampico grand reproducing piano by Rogers of London