Other brands of nicely designed old paperbacks are available:

And while this blog's policy remains resolutely pro-Penguin, a change is as good as &c.
Published by Doubleday Anchor, 1956. Noah Greenberg was founder and director of New York Pro Musica Antiqua, with whom Auden collaborated several times in the Fifties - providing an English narration for their path-breaking revival of The Play of Daniel, and recording An Evening of Elizabethan Verse and Its Music with them.
The book is beautifully produced, and has an introduction by Auden and Kallman (his young man) to the texts:
"The poet who would write songs is denied many poetic virtues, but he is also guarded from many poetic vices; he cannot be prolix or private or preachy or obscure. When one compares the poetry of the preceding age, so crowded with endless maundering allegories, with the poems in these song books, one cannot but thank God for men like Byrd and Dowland, in response to whose demands the poets were compelled to practice the virtues of graceful ease and conciseness."
There are critics who would claim that Auden's career was an instance of precisely the reverse process: graceful ease and conciseness giving way to the vices of prolixity, preachiness and obscurity. (I admit to preferring the early verse; but that doesn't mean I don't admire and value the knottiness of the later stuff - e.g., In Praise of Limestone - as well.)
I'm not sure what is keeping that lute from falling over, but the illustration is perfectly lovely. It's by Edward Gorey, of all people: see also here.