Any singer who opens a recital with Robert Schumann's "Dichterliebe" is obviously demanding serious attention. This cycle of 16 songs to superb little poems by Heinrich Heine portrays a young man, deeply in love, who is a different person every 10 minutes. It demands as much of the singer, technically and emotionally, as anything in the repertoire.

It is obviously a young man's music, in some ways a biography of Schumann's emotions in the months before his marriage. Still, a young singer must perform it, not with caution (seldom the right approach to Schumann) but with careful preparation. It is magnificent music, but not music for warming up.

Tenor John Lackey, a singer of considerable potential and a finalist in the young artists' competition of the National Federation of Music Clubs, had obviously prepared carefully before last night's recital with pianist Diann Clark at the Clarendon First Baptist Church in Arlington. He clearly knew what was needed, and his light, pleasant voice followed directions meticulously, with growing ease, power, flexibility and tonal richness in each successive song.

But at first, the performance was small-scaled and some of the values were more indicated than realized. It was not a flawless "Dichterliebe," but it was an interesting one, even if part of the interest came from watching the voice slowly warm to its task.

The second half of the program was considerably more satisfactory; after "Dichterliebe," Quilter's "Go, Lovely Rose," Britten's "The Birds," Duparc's "Soupir" or "Chanson Triste" and Bernstein's "Simple Song" from "Mass" are minor challenges. In that sense, perhaps "Dichterliebe" is good music for warming up--but any benefits to the singer probably do not outweigh the negative effects on the music.