LATE AT night the lovely woman touches the keys and a little Schumann floats forth, and the man (for music hath charms) lies down on the floor in the hall outside, to hear such melody.

It is, of course, a common evening scene at the apartment of Patrick Hayes, impresario, and his wife Evelyn Swarthout, pianist and professor, on sober old California Street.

Swarthout may practice at 11 p.m. Hayes often lies down, outside the room, not to disturb her, and to let the music remove, as you might say, the warts right off his soul.

It has been a happy marriage. Full of music.

For years Hayes (who established and directs the Washington Performing Artsa Society) has been a tuneable man.

He has brought everybody in the world here to sing to the capital. Artur Schnabel, Toscanini, the Bolshoi, Maria Callas, and the Lord only knows how many thousand others since he began this music management business 38 years ago.

"The last 10 years have been the best," he thinks. There was a dark time in 1960 when he almost quit the business "to go into the State Department or some other..." He was that down in the dumps.

But he held on. There is much to be said for staying power, which is a great thing in men, as well as in horses, roses and opera repertory.

And now he will be 70 next Tuesday.Tremendous bash for 63,000 select friends planned in the new theater of Kennedy Ceonter. Wow. Party time. Few in Washington are better known, hardly any better loved. I say it's trumpet time.