In this study we analyse two instruments of the 19th century, the Steinway piano owned by the Liszt Institute of Bologna (1860) and the one donated to Liszt in 1883. This comparison allows us to retrace the steps of the late-romantic Steinway research on the changes of the pianistic technique and the modifications of the concept type. We highlight previously unknown organological aspects as regards the passage between the double repetition Erard mechanic and the Steinway mechanic, by illustrating also quantitatively the typologically constructive modifications to the tone-colour. The acoustic analysis has allowed initial verifications of the modalities of the phonic functioning of the Steinway patentes of 1872 (Duplex Scale) and 1875 (Capo d’Astro Bar).