Leonard Bernstein's new recording of Liszt's "A Faust Symphony" and the "Prologue in Heaven" to Boito's opera "Mefistofele," is an achievement of such visceral excitement that, for once, one does not hesitate to use that loaded word "smashing." As Bernstein performs these two epic products of the musical avalanche spawned by Geothe's majestic poetic apotheosis of romanticism, they are smashing indeed - both esthetically and sonically.

The first and more theatrical book of Goethe's poem appeared in 1808 and the second, more philosophical one, came in 1833. With their publication, the quest by the learned 16th-century German doctor for youth and knowledge, even at the price of selling out to the devil, was reversed from sin (as in Marlowe's Elizabethan play) to virtue. Goethe's notion of Faust was an idea whose time had come, as it helped open the floodgates of romanticism and the character became a symbol of the romantic intellectual's search for truth and power. A multitude of musical and literary works poured through those open floodgates - not only Liszt and Boito, but Wagner, Berlioz, Schumann, Gounod and Mahler, to name a few.

It is safe to say that if Leonard Bernstein the composer had been around then he would almost certainly have written his Faust fantasy - given Bernstein's penchant - personal and musical - for the "big statement" and his audile predilection for the "big sound."

As for the Liszt and the Boito, Bernstein may not have written them, but he probably wishes he had, and, in the role of Bernstein the conductor, he plays them as if he owned them. Both works focus on the philosophical grandeur of Goethe's Book II, and it is doubtful that they have ever sounded grander than in these performances, which are on Deutsche Grammophon (2707 100 - two discs).

One does not make such an assertion casually, for in the Boito there is a performance by Toscanini (most recently on Victoria 1398, and unwisely deleted) so fine that one has hardly felt a crying need for competition. And in the Liszt, there is a superb if slightly faded Beecham on Seraphim and an earlier Bernstein, with the New York Philharmonic on Columbia. Here is a case of a conductor, with the Boston Symphony this time, conspicuously outclassing himself the second time around.

Boito's "Prologue in Heaven," the briefer work, is the first scene of an opera that subsequently comes down to earth and stays. Just in terms of sonorities, this drama "in the cloudy regions of space "is a huge extravaganza, with offstage clarion calls of trumpets, claps of thunder rather convincingly recreated in the percussion, and choirs everywhere - the Celestial Host behind a screen of clouds, a Mystic Chorus and the Cherubim. But don't be misled by the word extravaganza, for this scene is a musical masterpiece, seldom have such spectacular sonic effects been channeled into such deep and intense expression.

Bernstein's interpretation achieves a remarkable balance between splendor and dignity. The thunderclaps at the beginning are hair-raising. Then he achieves a quick, striking, contrast with the quiet serenity of the opening of the hymn to the Lord. The spicy orchestral glitterings are sharply pointed (particularly the harp and the snare drum).

The triumph is not just Bernstein's. The Vienna Philharmonic performs at its most sonorous, as does the chorus of the State Opera and a children's choir. Moreover, the Mephistopheles is that golden-throated bass Nicolai Ghiaurov, who brings a wonderful swagger to his mockery of God. Then there is the sound: It has clarity and power. Listen, for instance, to the point near the end where orchestra and choruses are going full blast and the organ adds yet another layer of sound. Smashing, indeed.

If Liszt's music isn't up to Boito's, it's because the "Faust Symphony" is only a partial masterpiece. In the notes Bernstein discusses the "disrepute" in which Liszt's orchestral music is held these days. While basically in agreement, he singles out this work as the one exception.

Almost an hour and a half long, it requires the kind of electric virtuosity that Bernstein at his best can generate to keep from dragging in places. Listen to the whiplike precision at the opening of the Mephisto movement, or the brilliance of the percussion in the repeat of this material. The Boston Symphony is one of the few orchestras capable of this, under Bernstein or anybody else.

One has no qualms about the second of the three movements, devoted to the maiden Gretchen. In fact, if only it survived alone among Liszt's orchestral output, one would conclude that he was one of the greatest of orchestral composers. Oddly enough, this composer known best for his pyrotechnics reaches his highest level of expressivity in music of melting gentleness. It reflects some of the child-like delicacy of Berlioz, to whom the symphony is dedicated, and anticipates the serene freshness of Mahler. The numerous repetitions of the principal theme are hauntingly phrased by the Boston Symphony's winds, horns and strings. And at the end of the last movement, Liszt resolves the conflicts by bringing this theme back, as a symbol of Faust's salvation through Gretchen, and uses it as the setting for the final lines of Goethe's poem, sung here by tenor Kenneth Riegel and the Tanglewood Festival Chorus.