Beethoven's quartets for piano and strings are among the least familiar of all his works. The first three were written as a set when he was only 14 years old and were not published until five years after his death. Sir George Grove assigned them the "unofficial" opus number 152; they are codified now as WoO (Werke ohne Opuszahl ) 36. About a dozen years after he wrote these three quartets, Beethoven composed his well-known quintet for piano and winds, Op. 16, and this work he also arranged as a quartet for piano and strings. He never composed another, either as an original work or as an arrangement.

All four of these quartets, so obviously modeled after Mozart and yet so rich in flashes of originality, have been recorded by the Bohuslav Martinu Piano Quartet of Prague in a new two-disc set from Supraphon (1.11.2211/2212) which is as attractive as it was unexpected. That the performances are first-rate may be inferred from a glance at the personnel listing: the ensemble named for the 20th-century Czech master (one of the few composers to write with distinction in this medium) is none other than the illustrious Vlach String Quartet, but with its second violinist replaced now by pianist Emil Leichner.

Leichner is a somewhat less sparkling pianist than Christoph Eschenbach, who has recorded the three early quartets with members of the Amadeus Quartet on a single Deutsche Grammophon Privilege disc (2535.174), but he is never less than satisfying, and the new set is really the DG version on all other counts (except, of course, economy). Despite Eschenbach's attractive playing and the smooth string tone of the Amadeus men, their joint effort gives the impression that they gathered in a recording studio to perform, for perhaps the only time in their lives, a clutch of boyish works they regarded as too slight to be taken seriously. The heavily accented, hard-driven playing is not representative of these musicians at their best, and the mushy sound, with the piano too far forward, is hardly a credit to DG's engineers.

The new Czech performances are relaxed enough to suggest genuine familiarity with the material. These players seem to have found a good deal worth savoring, and they make it hard for any listener not to share their enjoyment. Their tempo for the opening movement of No. 3 may not conform to the marking Allegro vivace, but it happens to fit the spirit of the music ideally, and the final movement of this work as set off here is utter deliciousness. The strings are well integrated with the piano throughout the set, enabling the warmhearted charm of these agreeable pieces to make its full effect.

Personally, I could dispense with the string version of Op. 16, but it makes a most appropriate fourth side here, and having each of the three WoO 36 quartets on a side to itself makes for much more enjoyable listening than the "sandwich" layout offered by DG. These are not major works, by any means, but their presentation here is altogether distinguished.

Similarly distinguished is another two-disc Supraphon set in which the Suk Trio performs the three piano trios of Brahms (Opp. 8, 87 and 101); side 4 is given over to the Horn Trio, Op. 40, in which violinist Josef Suk and pianist Jan Panenka are joined by Zdenek Tylsar (1.11.2251/2252).

Suk recorded the Brahms trios with Janos Starker and the late Julius Katchen for London-/Decca nearly 15 years ago. There is some beautiful playing on those sides, but the music hangs together more convincingly in the new set from Prague, and this is hardly surprising when we consider how long the Suk Trio has been playing this material. Tylsar, the principal horn of the Czech Philharmonic, does not command the opulent tone of a Barry Tuckwell, who has recorded the Horn Trio with Itzhak Perlman and Vladimir Ashkenazy on London CS-6628, but to my ear he and his associates are more at home in the work, which tends to sound overdriven to the point of breathlessness (on the part of the listener, not the remarkable Tuckwell) in the fast sections on the London disc.

The matter of tempo, in fact, is one of the basic elements in the success of this Brahms set, as in that of the Beethoven described above; it is virtually ideal everywhere, and so is the articulation of every phrase in these well beloved works.