The young French pianist David Fray has become known almost as much for his onstage "antics" as for his sublime playing. YouTube doesn't give much away with respect to the former, so San Franciscans can make their own judgments about what, if anything, the hyperkinesis signifies when Fray joins the Symphony for a romp through Beethoven's Second Piano Concerto May 5-8. I have it on authority that the pictures don't lie, and now, with his new CD of Schubert miniatures for Virgin Classics, all the evidence I need that Fray's a pianist of the first caliber.

The two major "acts" of my concert-going years – Kennedy, who could turn the stage into a mosh pit while spinning off Elgar of gravity-defying sublimity; and Matthias Goerne, who mimics a one-man Eiko and Koma show while seemingly ventriloquizing Schumann at his most keeningly desperate – haven't bothered me a bit with their extramusical extravaganzas, which in any case didn't seem extramusical to them. I can't imagine minding watching Fray do anything.

Funny business couldn't be farther from the arena in Fray's new CD of Schubert's Moments Musicaux, D780, and the four Impromptus of D899. Playing with the kind of technical authority that takes your attention completely away from thoughts of flesh on ivory, Fray plunges into the deep, most often melancholy-feeling realm of these astonishingly universe-creating little pieces. More than once, forgetting that this was piano-playing going on, I wondered if Fray had the breath to make it to the end of one of Schubert's protracted, off-to-the-stars phrases.

But it's precisely what Fray does have: the concentration to hold the whole of these pieces in his mind so he can conjure the colors hidden behind the black of each note and the infinitely flexible rhythmic realms in the white spaces beneath them. The playing never sounds saturated, just single-minded in the highest sense of the term. Whatever pirouettes he takes to the stage, there isn't a hint of exhibitionism or the merest mangle of mannerism in his playing in the studio, which is just so right you gasp.

It's daring in ways you don't even know until Fray has ferried you safely across the gorge. When he starts drawing the tendrils of sound out of the shockingly simple, naked opening octave of the G-Flat Major Impromptu, you just want to shout, "No, go back. If you begin that beautifully, you'll have nowhere to go." But Fray finds nothing less than a cosmos opening up before him, his to wander as his courage allows.

Brooks and streams, flowing water, the image so omnipresent in Schubert, seems to guide and inform Fray's playing. Its unforced naturalness and deep, inner energy give the playing its sustaining impulse. Borne along by that flow, and utterly vulnerable to it, he explores dimensions of feeling open to few people. You would not conclude from these performances that the piano is a percussion instrument, except in the way that it taps your heart.

By contrast with Fray's extraordinarily fine-grained playing, the Belcea Quartet's new Schubert double-CD (EMI Classics) is rough trade. But the result is chamber music as vital and gripping. The Belcea, too, studiously avoids eccentricity and plays the scores as written, and even with a sense of having absorbed the lessons of historically informed performance. And then they just clobber you with the music.

Their performances haven't – yet, anyway – displaced my previous favorite recordings of the sublime C-Major String Quintet (the Belcea's, with Valentin Erben the second cellist) and The Death and the Maiden. But I'll guarantee you, you won't be thinking about other performances while you're listening to playing as trenchant, persuasive and heartfelt as the Belcea's. It strains credibility that these are studio recordings. With no sacrifice of beauty as traditionally defined whatever, these performances bite.

I wouldn't want to be without these performances of the pieces already mentioned, yet the revelation of the set is the Belcea's hot-to-the-touch performance of Schubert's final String Quartet, in G, D998. This is, for my book, playing at the very edge of what is endurable. The superbly executed skittering figures throughout the first movement whirl like dandelion ghost flowers one minute, then return like a swarm of menacing jungle insects the next.

This death-drenched music – impending death; sudden death; pervasive death; death the real McCoy – has visceral impact in the Belcea's interpretations, which are equally shocking for the precision and finesse of their execution. It's not going too far to call this playing death-defying, and if you have the emotional wherewithal to bear with them though the final movement, some of the most emotionally uncompromising and psychically discomfiting music ever composed, give yourself some credit for emotional maturity. You can always go back to the Quintet for the glimpse beyond.