His love of music, experience, and ear for harmony make him a great musician.
His love of music, experience, and ear for harmony makes him a great musician.
Are both sentences grammatically correct? In my opinion, they are, and the only difference between the two sentences is in the first one, the musician's three traits/skills are perceived as individual elements, whereas in the second one, the three elements are seen as one thing.
Am I right in my interpretation of the two sentences?
No, I don't think there's a way of supporting a singular verb here.
It is true that sometimes there can be phrases that combine multiple things into a single recognized entity, but they have to be consistently, universally recognized as "one thing":
PB & J is a good sandwich.
Ben and Jerry's is a popular ice cream company.
Cookies and Cream is their best flavor.
I think I'm hungry today. Anyway, these things work because these phrases are used as units so often that they "fuse" together, and are treated as singular in these sentences (in fact, the possessive in "Ben and Jerry's" doesn't even have any effect).
It's also true that sometimes there can be a singular noun that is made up of multiple parts:
Lucy and Ricky are my favorite couple.
... but even there, the verb will depend on whether the whole or the parts are the subject of the sentence. Above, "Lucy and Ricky are." Change the order, and the verb changes too:
My favorite couple is Lucy and Ricky.
Since the subject of your sentence is three things that are not universally recognized as one thing, it must take a plural noun. If you wanted, you could keep the idea of thinking of them as one thing by rearranging your sentence to make that idea the subject:
His winning combination of love of music, experience, and ear for harmony makes him a great musician.
