Which of the following is NOT a notable feature of Romantic orchestral music?

In Romantic orchestral music, one of the defining characteristics is the increased emotional expression that composers aimed to convey, representing a departure from the more restrained emotional content of the Classical era. This period is also noted for its use of rich orchestral color, where composers expanded the orchestra and utilized various instruments to create a wide range of timbres and dynamics, allowing for more nuanced emotional communication.

Moreover, the exploration of new thematic material reflects the Romantic composers' desire to express personal and unique ideas, often drawing inspiration from literature, nature, and intense emotional experiences. This exploration led to innovative approaches in melody and harmony that were not typically found in the strictly structured classical forms.

In contrast, strict adherence to classical forms is not characteristic of the Romantic period. Composers during this time often broke away from the conventional forms established in the Classical period, favoring more freedom in structure to serve their artistic expression. This highlights why adherence to classical forms does not align with the notable features of Romantic orchestral music.