Young Anne-Sophie Mutter's recent performances of Mozart's G-major Violin Concerto with Rostropovich and the National Symphony Orchestra constituted brilliant assurance that what we heard in her Deutsche Grammophon recording of the work with Karajan and the Berlin Philharmonic was all real. r

What was so striking was not that a 16-year-old can play the violin so well (she was only 14 when she made the recording), but that a violinist of any age combines such rich musical insight with such formidable technical power. Her tone is a near-miracle of purity (it happens also to be very big and warm), and she seemed to be playing always from inside the music.

Now it appears that this young German is not a solitary phenomenon, for there are other superb young string players emerging in Central Europe. One is the Salzburg-born Thomas Zehetmair, who is two years older that Mutter and also had made a Mozart record. Zehetmair waited till the ripe age of 16 for his formal debut in his (and Mozart's) home town; but to make up for the "delay," he supplies his own cadenzas in the Violin Concerton No. 1 in B-flat (K. 207) and the Sernade No. 3 in D(K.185), the two works he performs with the Mozarteum Orchestra under Leopold Hager on Telefunken 6.42537.

This is an imaginative bit of programming, for neither work is heard very often, but a violinist of Zehetmair's quality would be just as welcome in the most overexposed pieces in the repertory. K. 185, the first of Mozart's really big orchestral serenades, incorporates a miniature violin concerto in the second and third of its seven movements and there is a further solo episode in the second of the two minutes. Hager's approach in the Serenade is a bit more expansive than Will Boskovsky's (London STS-15171); and that, combined with Zehetmair's exceptional fiddling, invests the work with a bit more substance. The record is an out-and-out joy, and all the more attractive, of course, for offering material so unlikely to be duplicated in most collections.

Another most impressive debut record, made up of more familiar material, is a Supraphon import (1-11-1683) on which the Panocha Quartet of Prague perfoms Haydn's Quartet in D, Op. 64, No. 5 ("The Lark"), Schubert's Quartettsatz in C minor, D.703, and Dvorak's so-called "American" Quartet in F major, Op. 96. Since we are accustomed to more "unified" packaging, coupling Haydn with Haydn, Schubert with Schubert, etc. this amy look like an odd assortment, but it is the very sort of mix one encounters in an acutal recital program, and makes for a handsome demonstration of the ensemble's aptitude in different areas of the reprtory.

Jiri Panocha, the first violinist, formed the quartet in 1968, when he and his three associates were students; some of them must still be under 30. The recording was made back in the spring of 1974, and one can only wonder why it has taken so long to reach us. I do not know a more affecting performance of the Dvorak, a more subtly seasoned one of the Haydn, or a more dramatically flowing one of the Schubert. The sweetness of the violin tone in particular, and the smoothness and spontaneity on the part of all four participants are as striking as these qualities are from Mutterer, and the level of integration achieved in these performances is hardly less remarkable, for a string quartet of such young players, than the solo excellence Mutter and Zehetmair show at barely more than half their age.

The Czech recording is especially rich and well balanced, and the surfaces are very quiet. Those who find this particular combination of titles convenient need not hesitate to pick up this record and start enjoying it.