The music of Ernest Bloch now occupies nearly a full column in the Schwann Record & Tape Guide. His representation on records has been growing slowly, unspectacularly, year by year. There are now approximately twice as many recordings of his music as there were 10 years ago, and this slow growth should continue. His music is seldom spectacular, always solid; he composed only when he had something to say, and he said it eloquently and succinctly. His style is recognizably modern but always perceptibly a continuation of the great musical tradition that dates back to Beethoven.

Some of the recognition Bloch deserves will be given tonight and next Sunday in a pair of free concerts at the National Gallery of Art, with the Portland String Quartet performing all five of his quartets. It should be, as National Gallery concerts so often are, a significant statement about a corner of our musical heritage that does not receive enough attention.

The Portland Quartet has already made Bloch's quartets available in a recording (Arabesque 6511-3, three LPs) that belongs in any serious collection of 20th-century chamber music. The quartets of Bloch, like those of Walter Piston that the Portland Quartet is now recording for Northeastern Records, are a significant enrichment of the repertoire.

The performance is totally suited to the music -- deeply serious, technically expert, free of flashy showmanship and emotionally expressive. This set gives deep and lasting satisfaction.

Charles Dutoit, the Montreal miracle man, is currently guest-conducting the National Symphony in the First Symphonies of Schumann and Mahler. Beginning Thursday, the program will change to Fifths by Prokofiev and Beethoven. Beethoven's Fifth Piano Concerto will be performed when Daniel Barenboim is available as a soloist and his Fifth Symphony when Barenboim is busy conducting "The Marriage of Figaro" for the Washington Opera. Schedules are complicated on the classical music fast track.

Like Barenboim, Dutoit has been on that track for some time. In his six years in Montreal, he has converted the humdrum Montreal Symphony into the Orchestre Symphonique de Montre'al, suddenly an international power in classical recordings and one of the most elegant orchestras in North America. He also has become one of the world's busiest guest conductors.

What he is doing in Montreal seems to parallel what Mstislav Rostropovich is doing in Washington. Rostropovich's ambition (at least one of his ambitions) is to build the world's finest Russian orchestra in the capital of the United States. In Montreal, Dutoit seems to be intent on building the world's finest French orchestra. His current recordings indicate that he is well on the way to achieving that goal.

His repertoire with the Montreal orchestra on two current London records is about as popular as classical music can be. On London 410 253-1, it is Rimsky-Korsakov's "Scheherazade" and "Capriccio Espagnol"; on London 411 708-1, Offenbach's "Gaite' Parisienne" and Gounod's "Faust" ballet music -- bright, lively and colorful pieces that demand brilliant technique from the orchestra, total control from the conductor and impeccable sound engineering.

Dutoit faces the stiffest possible competition in these records, and he matches it impressively, with first-class assistance from the recording engineers.

The most memorable guest conductor the National Symphony has had in many seasons was Klaus Tennstedt last year. He was back last night conducting the London Philharmonic in Mahler's Fifth Symphony and Schubert's "Unfinished." Two of his recent recordings with the London Philharmonic, just made available on EMI compact discs, will help preserve memories of his outstanding musicianship until he conducts here again.

In the First Symphony of Brahms (EMI CDC 7 47029 2), his interpretation is thoughtful, weighty, beautifully controlled in concept and ensemble playing. The underlying structures of this symphony, its artfully constructed tensions and resounding resolution, are perceived with great breadth of vision and precision of detail. His tempos are more deliberate than one usually hears, but he maintains the sense of line and continuity beautifully. He presents the essential deep seriousness of this music in a style as compelling as any conductor since Otto Klemperer -- with, of course, enormously better recording than Klemperer enjoyed.

The special clarity and wide dynamic range of digital recording are even more important in Mahler's Second Symphony ("Resurrection"), where Tennstedt and the orchestra are joined by soprano Edith Mathis, mezzo Doris Soffel and the London Philharmonic Choir (EMI CDS 7 47041 8, two discs).

The symphony has come into its own in the past generation. The reason for its current popularity may be that its central question is whether man can survive -- an issue more topical today than it was when the work was completed 90 years ago. In any case, it now has more than a dozen recordings in the Schwann Record & Tape Guide -- the kind of duplication that once was available only for Beethoven's Fifth or Tchaikovsky's "Pathe'tique."

Among so many interpretations, it is impossible to pick a single best, but Tennstedt's is certainly among the top contenders, not only for the quality of the conductor's vision but for the musicianship of the performers. It is thoughtful, sensitive and beautifully performed. The sound, on EMI's compact discs, is quite simply the best I have heard for this music. No symphony presents more challenges to recording engineers; the textures and perspectives range from full orchestra and chorus to solo voices and instruments -- sometimes alone and sometimes emerging from a muted orchestral fabric. The music has moments of enormous grandeur, but the passages that lodge themselves most vividly in the memory are the quiet, thoughtful ones -- chamber music with hundreds of performers on the stage.

The detail is beautifully worked out in the performance and captured with fine precision in the digital sound. This is a recording to delight serious listeners.