A night spent with someone leaves the speaker on the edge of something bigger than the night itself. The music is almost there. "I almost hear violins" is a small, honest admission: the feeling is close to romantic, even cinematic, but it never quite arrives.
What the speaker does get is fragments. Instead of clear words, there are "out-of-order voices," as if memory or conversation has been shuffled. The last image, "the whole lost press / of an instrumental wall," suggests a thick surge of sound, like strings swelling into a wall, that has slipped away or can't be recovered. The word "lost" gives the poem its ache.
The mood is wistful and a little dreamy. The speaker seems moved but also shut out, close to something intense without being able to grasp it fully. Judging by the imagery, the poem is less about what happened than about the blurry, unfinished way it lingers afterward.