The fiasco with quadraphonic discs was brought about not by any basic lack of soundness in quad per se, but simply by the record industry's gross irresponsbility in failing to agree on a single basic system, as it did, to its credit, in launching stereo. Thus it would be understandable if record collectors were to regard digitally mastered discs as just another gimmick to revive faltering sales. Understandable, perhaps, but certainly regrettable, for pulse code modulation (PCM) is surely the most significant and valuable advance since the introduction of electrical recording some 55 yeras ago.

Moreover, while the digitally processed discs themselves are expensive (up to $17.98 each), no additions to or modification of basically good two-channel playback equipment are required -- and, while there are several different digital systems, all are genuinely "compatiable."

Angel's first digital release, using the process developed by its English parent company, EMI, offers the London Symphony Orchestra's performances, under Andre Previn, of Debussy's three "Images pour orchestre" (Giues; Iberia; Ronde de printemps) and "The Afternoon of a Faun" (DS-37674, list $10.98). I like the sound; it is very much like that of Nippon Columbia's pioneering Denon series, which is to say, extremely smooth, transparent and well balanced, rather than emphasizing (or exaggerating) dynamic contrasts for their own sake. While I find Martinon's (Angel) Haitink's (Philips) and Baudo's (Supraphon) performances of the "Images" a little more fetching than Previn's, his are certainly competitive, and the stunning sound may be the deciding factor for many collectors.

RCA started out with Soundstream (Ormandy's Bartok Concerto for Orchestra), but has been using the Sony PCM system in its Dallas Symphony recording under Eduardo Mata. While this system, like other digital approaches, definitely scores in terms of freedom from distortion and background noise, it has a somewhat dullish character. When I compared the English Unicorn discos of Gliere's "Illya Murometz Symphony," recorded in this system, with the Barclay-Crocker tapes of the same performance, dubbed from analogue masters, I found the latter far more attractive for all-round brightness and presence. Any digital recording of Ravel's complete "Daphnis et Chloe" score ought to be a knockout, but the dullish character of the otherwise clean sound is no help at all to the energetic yet curiously lifeless performance under Mata on RCA ARC1-3458.

Telarc is one of the several adventurous smaller companies using the Soundstream process. I was less enthusiastic than some of my colleagues over this label's recent "1812" with Erich Kunzel and the Cincinnati Symphony, because the dynamic contrasts are so extreme that even with the most sophisticated quipment one has to "ride gain" to avoid damage to the amplifier and/or speakers. However, the brand-new release of Bizet's "Carmen Suites" and Grieg's "Peer Gynt Suites" (in each case, Suite No. 1 complete, with the two big numbers of Suite No. 2), played by the Saint Louis Symphony Orchestra under its new music director Leonard Slatkin (DG 1004S), can only be called a gem. The sound is superb, and so are the performances. "Anitra's Dance" here is given in its original 11-instrument setting, and the "Carmen" pieces are brought off with such polish and subtlety as to call for comparison with the recent Ormandy disc (RCA ARL1-3343), hailed as an aural handbook on the art of conducting.

Finally, from Denon, there is the latest installment in the Smetana Quartet's digital survey of all the Beethoven string quartets, this time Op. 59, No. 2, in E minor (OX-7178-ND). Some of the tempi in the last two movements may not be everyone's cup of tea, but in general this is a distinguished addition to a distinguished series, and both the realism of the sound and the balance between the instruments are pointed illustrations of the Denon system at its very best.