The Washington Bach Consort has returned from its trip to Europe with a poise and a performing edge it didn't have before it left. All this is to the good. It gives the musicians innate musicality, earnestness and diverse talents of a professional sheen. It can also present some problems, however, as occasionally was the case during the performance at the Washington Cathedral last night.

The big piece on the program was the "Magnificat" in a carefully drawn, lightly sketched performance that, despite the cathedral's acoustical traps, survived with contrapuntal integrity intact.

Conductor J. Reilly Lewis has his forces beautifully under control. They jump at the merest flick of his baton, so that the big entrance on "Fecit Potentiam" that comes after the gentle "Et Misericordia" was not upstaged by any leap or punch from the podium.

But there were times when the chorus resorted to instrumental tricks that did the music no favor at all. There were overly detached lines in "Fecit Potentiam." The trumpet played the same line beautifully, and it would have been nice if the chorus had matched it. There were exaggerated two-note phrases that made the "Esurientes" choral trio sound lumpy, a technique that, in other acoustical situations, might have been effective.

Write these problems off to new-found virtuosity, for certainly they could not take away from the excellence of the rest of the choral singing, the generally high level of solo performances or the splendid playing of the orchestra.

The program also included a performance of the motet "Komm, Jesu, Komm" from the balcony at the west end of the nave, about a block-and-a-half from the audience. By the time the sound got to the listening ears, it had deteriorated into a sort of silhouette of the music, lovely in an eerie way but, ultimately, not very interesting. There was also a nice Sinfonia from Cantata No. 42 and a sparkling performance, by organist William Neil, of a G Major "Fantasy" that was both delicate and powerful.