A noteworthy performance of Mozart's Requiem highlighted an all-Mozart program by the Prince William Symphony Orchestra with the Arlington Metropolitan Chorus and four fine soloists Saturday night at Gar-Field High School.

In choosing Mozart, a composer whose music is much harder to play than it sounds, music director Joel Revzen provided both a challenge and an opportunity for his orchestra to show off some of the growth that has taken place since he began his appointment this season.

Most apparent was the sense of ensemble. In the opening work, Mozart's Symphony No. 25 in G minor (K. 183), popularized as the opening music in the movie "Amadeus," all sections seemed on the same wavelength, both in phrasing and balance. A reduced number of strings (about seven on a part) lent a transparent texture, and all inner lines were audible.

Revzen took a very brisk tempo in the first movement, and with beautifully pungent oboe lines played by David James that soared above the busy strings, it was quite exciting. James's work was even more outstanding in the trio to the Minuetto. The strings also played very well. In some of the faster spots, some opening phrases sounded rough, but when the phrase repeated or continued, both intonation and phrasing improved.

The cellos and basses played with excellent articulation, but could have been more graceful. All in all, though, it was a fine interpretation of a very difficult and exposed piece of music.

Revzen's choice of the Arlington Metropolitan Chorus, which was prepared by its music director, Barry S. Hemphill, was ideal for the Requiem. The group has a mature but very integrated sound, clear but never intrusive diction and exemplary flexibility (the "Kyrie" was taken at breakneck speed, but every note could be clearly heard).

Some phrases were of breathtaking beauty, such as "Salva me" in the section "Rex tremendae" and the "Amen" to the "Lacrymosa." The warm sound of the tenor section was particularly lovely and appropriate: In some works a more ringing sound might be preferred, but amid the subtleties of this performance, it would have been intrusive.

The solo quartet also was excellent, with good blending of voices and very musical phrasing. The differences among the singers were apparent only during their solo lines, which is to their, and conductor Revzen's, credit.

Soprano Joanna Johnston was nothing short of spectacular. She is a singer who certainly understands Mozart and can communicate her understanding to the audience. Her sound was like warm honey, with a purity of tone and just a hint of darkness that was remarkably ingratiating.

But best of all was her musicianship. She sang each phrase as though it was the most beautiful and perfect phrase ever sung, and it became just so.

Bass Jon Nordstrom had a pleasing and robust sound and sang with authority, while tenor Keith Alexander sounded sweet and very even, although a bit light at times. Mezzo soprano Christine Thomas, fine in the ensembles, showed some rough edges in her solo lines.

The orchestral playing in the Requiem also was, for the most part, at a very high level (the group was up to its full complement of strings). A few string intonation problems were apparent in the "Rex tremendae," but on the whole it was a remarkably even performance. James's oboe again stood out as did the clarinet work of John Colbert and Nan Lopata, whose smooth playing over the strings in the opening section did much to create the atmosphere for the rest of the piece. Robert S. Mesite's trombone solo in "Tuba Mirum" was on the harsh side for this reviewer's taste, but certainly was within the realm of reasonability to summon the dead to the throne of God.

Conductor Revzen pulled together all the elements into a cohesive structure that was, truly, greater than the sum of the already quite fine parts. The timing between movements, the tempos and the dynamics were all beautifully executed to create a single work out of the dozen individual sections. It was a well-crafted and memorable performance.