Johann Nepomuk Hummel (1788-1837) displayed such a talent as a pianist when he was 7 years old that Mozart himself took him into his own home as a live-in pupil for two years. Later Hummel became known as one of the most brilliant of all keyboard artists, a composer of substantial and charming music, an outstanding pedagogue (Liszt, Czerby, Thalberg and Henselt were among his pupils), and one of the most beloved musicians of his time. He was one of Beethoven's very last visitors, and he received the dedication of Schubert's magnificent final sonatas.

During the last two or three decades there has been an intriguing, if hardly explosive Hummel revival on records -- to which the Musical Heritage Society has added now the two "Grand Serenades," Opp. 63 and 66, for violin; clarinet, bassoon, guitar and piano, played by members of Dieter Kloecker's Consortium Classicum (MHS 4195).

Although each of the serenades runs only about 19 minutes, the first is in no fewer than 11 movements and the second is in seven. What is most unexpected is that nearly every section is either a "paraphrase" or in outright transcription of music by another composer. Among the sources are the operas for Mozart, Rossini, Cherubini and Spontini, as well as pieces by such lesser lights as Francois Joseph Nadermann and Peter Joseph von Lindpaintner. One section in Serenade No. 1 compromises variations on a Cherubini theme by Mauro Giuliani, Joseph Mayseder and Hummel himself.

The tunes themselves, needless to say, are all attractive, and the instrumentation makes for some unusually ingratiating effects. The documentation is not all it might be -- a misspelling here, a curious credit there, the opus numbers nowhere mentioned -- but the perfformances are extremely persuasive and the sound (from Seon) is first-rate. If this doesn't become the chamber-music "sleeper" of the year I'll be surprised.

I wouldn't be at all surprised if Max Reger's sprawling Third String Quartet, in D Minor (Op. 74), failed to be quite so well received. But it's good to have it available, also from MHS, in a sympathetic and well recorded performance by the Zagreb String Quartet (MHS 4186). For the last dozen years or more MHS has been releasing the German Da Camera recording of all of Reger's chamber music and solo instrumental works, more than 30 discs so far; this appears to be the premiere recording of the D Minor Quartet.

Reger was clearly in no hurry to make his point in this work, but it is the sort of thing that can grow on anyone interested enough to listen to it twice. Toward the end of the 21 1/2-minute first movement there are some apparent reminscences of Beethoven's Op. 131 Quarter. The scherzo that follows in one of Reger's most effective pieces in that form, and the slow movement, an Andante with variations, has real depth as well as unstrained communicativeness. Only the final movement seems a little inconclusive, but it is by no means without appeal.

Again there are some lapses in the documentation, the most bothersome being the failure to tell us when the Quartet was written and the implication, by omission, that this was Reger's only essay in this form. (He wrote five string quartets; the two earlier ones were issued in this series several years ago, but there is no reference to them in this presentation.) Again, however, these are minor irritations which ought not deter anyone from investigating this release.

Still more from MHS, and especially welcome, is a two-disc set of four symphonies by Muzio Clementi, performed by the Philharmonia Orchestra under Claudio Scimone (MHS 4150/51). There are the same performances that were available all too briefly (only a few weeks, it seemed) on Erato pressings imported from France by RCA early last year. The set became something of a collectors's item then, and those who missed out on it will be happy to have the recordings more permanently available. The MHS pressings don't quite match the sound of the imports, but they are quite good in their own right, they cost only about half as much as the imports, and they are available. More conveniently packaged, too, in a space-saving gatefold container instead of a big box, and the original annotation is preserved, with only minor cuts. Highly recommended and well worth the bother of ordering by mail.