Pianist Gwendolyn Mok is into the Big Bang behind musical compositions. What was it that led Beethoven or Ravel to create their "sound worlds?" she asks. Here's what she thinks: Music often rises out of the partnership between a composer and a piano -- the specific one at which the creator sits at home, noodling, working out chords and melodies and meticulously constructing a musical work.

Her latest object of fascination is Johannes Brahms. "Listen to this," she says. "This is going to knock your socks off."

Mok -- who has a brand-new recording of Brahms' late piano works and is exploring his "sound world" with several concerts, starting Sunday -- is in her studio at San Jose State, where she runs the keyboard division. She is seated at a piano built in 1871 in Vienna by Johann Baptist Streicher, who also built a nearly identical grand piano chosen by Brahms for his Vienna apartment in 1872.

Mok lets it rip: The thick chordal textures of Brahms' Intermezzo in A major, Op. 118, No. 2, open up, ripe and golden-sounding. It's impossibly sad music -- "interior" is the word Mok uses to describe Brahms' late works. This one seems to rise from the composer's famous passions and missed love opportunities. Its inner voices -- entwining lines, ever moving -- can get muddled when performed on modern grand pianos, powerful machines that sometimes overwhelm a listener. But played here by Mok, the voices are vivid.

"It's ridiculous, how clear it is," she says, jumping from the 142-year-old keyboard to a neighboring piano, a modern grand, on which she plays the same Intermezzo: "Doesn't that sound like mush?" she asks. "Sounds like mashed potatoes. But on the Streicher, it's like all the gunk has been removed from an old painting. It has warmth, and now I feel like I get Brahms' sound, his timbres and textures."

Mok plays this Streicher piano on her new "Brahms, Late Piano Works, Opp. 116-119: The Composer's Piano" on the MSR (Musicians Showcase Recordings) label. It's a strikingly fresh recording, cracking Brahms open so that listeners can get to know him anew. On it, she also enlists her own 1868 Érard grand piano, built in Paris. Famous for their harplike sonorities and "double escapement action" (allowing for the rapid repetition of notes), Érard pianos also were a favorite of Brahms. On one occasion, he refused to perform his own Piano Concerto No. 1 in Hamburg, Germany, unless he could play it on an Érard.

For Mok, these historic pianos are magic carpets, helping her "bring this new world of sound to my public," she says. "We're always trying to teach students how to make a beautiful sound, a warm sound. But it's a very limited world of sound that we're promoting when we only perform on modern pianos. It would be as if you were teaching painting and you were limited to certain palettes of color."

Mok, who lives in Berkeley, grew up in New York, attended Juilliard and built a busy career, which included recording with London's Philharmonia Orchestra -- and, in 1993, meeting pianist Vlado Perlemuter, a protégé of Maurice Ravel, who guided her through that French composer's world. Guess what she learned? Ravel composed -- "painted in sound" -- on an Érard. Its sound was his sound and became her sound. In 2001, Mok recorded "The Complete Works of Maurice Ravel" (on the MSR label), playing her own Érard.

Leading San Jose State's keyboard division, Mok has helped build her department's impressive collection of historic keyboards, which also includes an 1841 Bösendorfer and an 1861 Érard built in England.

(She points out that the Ira F. Brilliant Center for Beethoven Studies, on campus, has its own collection, including an 1823 Broadwood fortepiano like one on which Beethoven composed. Mok is considering a recording of Beethoven works using it.)

Anyone who attends Mok's upcoming Brahms concerts in San Jose or Berkeley will see her perform on her 1868 Érard. (At Monday's CD launch concert at San Jose State, she will play the Streicher, too.) She will bring along her musician friends -- members of the San Francisco Symphony, the San Francisco Opera Orchestra, the San Jose State faculty -- varying the cast from program to program. The Berkeley event, on April 27, will feature former U.S. Poet Laureate Robert Hass reading favorite poems on music.

For Mok, it's all about the pursuit of sound -- "as much an education for me as it is for my students or the listening public." That's her mission.

Contact Richard Scheinin at 408-920-5069.

Pianist
Gwendolyn MoK

In a series of all-Brahms programs
When/where: 7 p.m. April 14, Le Petit Trianon, 72 N. Fifth St., San Jose; presented by San Jose Chamber Music Society; $27-$42,
408-286-5111,
www.sjchambermusic.org/tickets.php
When/where: 7:30 p.m.
April 15, San Jose State
Music Concert Hall, on campus; CD release concert; $10-$20 at the door
When/where: 8 p.m. April 27, Hillside Club, 2286
Cedar St., Berkeley; $25,
www.brownpapertickets.com