Final answer:
Niccolò Paganini is the musician who inspired Franz Liszt to practice intensively, leading to Liszt's own rise as a virtuoso pianist and composer in the Romantic era.
Step-by-step explanation:
The musician who awed Franz Liszt at age 19 and inspired him to practice 8 to 12 hours a day was Niccolò Paganini. Paganini was known for his extraordinary technical prowess on the violin and was one of the first 'pop star'-type stage personalities of the nineteenth century, much like Liszt himself.
His performances left a lasting impact on Liszt, who was greatly influenced by Paganini's virtuosity and stage presence. This inspiration prompted Liszt to dedicate himself to becoming a virtuoso on the piano, in a similar vein to Paganini's command of the violin.