Get out the microscope, because we’re going through this poem line-by-line.
Or triumphal chant,
- The speaker is in full smarty-pants mode here—showing off what he knows about poetry. These are just two different kinds of poems meant for different occasions.
- A "Hymeneal" chorus is a poem or a song for a wedding (Hymen was the Greek god of marriage).
- A triumphal chant would be written to celebrate a victory.
- There, not so complicated after all, right?
Match'd with thine would be all
But an empty vaunt,
- As far as the speaker is concerned, all this human poetry can't stand up to the skylark's tune.
- In comparison, poetry would just sound like meaningless boasting ("an empty vaunt").
A thing wherein we feel there is some hidden want.
- Those empty boastful poems or songs would just make us feel like something was missing (a "hidden want") compared to the skylark's incredible melodies.