I think musical meaning is contextual. It is meaning for someone particular at a particular time. The meaning of a piece of music is whatever the listener says it is, simplistically speaking. [This is true even if we have an internationalist view of meaning: we still have to posit a listener reconstructing an intention. It still has to be a meaning for someone.] It is pointless to invest too much in one's own interpretations, or to argue that others' interpretations are not valid ones.
The meaning of music directly tied to a literary text will be an extension of the meaning of the text. In other words, since literary meanings are much more directly semantic, they will strongly condition the reception of the musical meaning, providing a set of cues. We can talk about this musical meaning in tension with the meaning of the words of the text, but in that case we will talk about the setting as being inappropriate to the text, not vice-versa.