I've listened to this CD over and over again, trying to understand what made it work. There is a historical precedent for the pairing of Beethoven and Stockhausen but that's only of intellectual interest, not a path toward artistic success. I considered whether it might that the pianist Pi-hsien Chen operated like a good DJ, successfully segueing between dissimilar songs but that didn't add up: the program on her Klavierst�cke Sonaten CD simply alternates between the two composers � a good DJ doesn't double back. When it finally struck me what made the record so enjoyable to listen to, I laughed at how obvious the answer was.

The historical precedent for the project is a concert Stockhausen himself gave in D�sseldorf in 1970 as a part of the bicentennial celebrations of Beethoven's birth. (What respect the avant gardists showed! Mauricio Kagel also made his wonderful film Ludwig Van that year.) Stockhausen was initially invited to give a lecture but instead reworked his Kurzwellen to have the musicians respond to fragments of Beethoven's music via headphones rather then the radio signals he initially used. The concert was televised and released on record and, according to Christopher Fox's liner notes to Chen's album, roundly considered a flop.

What Chen does is take the Beethoven out of the headphones and places Ludwig and Karlheinz alongside, rather than on top of, one another. The program alternates between sections of Stockhausen's Klavierst�cke and Beethoven's piano sonatas in A Major and C minor. She merely presents the evidence, leaving the intrinsic connections Stockhausen proposed for the listener to discover.

That alone doesn't make for a successful program. The notion of Chen as a clever DJ, however, is not entirely off-base. After the first four of Stockhausen's angular Klavierst�cke, she launches into the immediately recognizable opening strains of the Sonata in A Major. She plays with a delicate assuredness, but the thing that makes the CD so great first happens at the beginning of the third adagio movement. As she plays the few, initial, isolated notes of the piece, there's a feeling that she's returned prematurely to the Klavierst�cke. She has, it seems, found the Stockhausen in Beethoven. Then, after the plucky fourth movement, the fractured formalities of Klavierst�cke V sound a little more Beethoveny. A quick jump backwards again for the Sonata in C minor is warmly welcome but not out of place. The final Klavierst�cke VI comes off as more resonant than dissonant.

So has Chen isolated some particular that connects the two composers, separated by a century and a half? Maybe, but in truth, probably not. The connection here is the pianist herself, deftly approaching the diverse works as if there were no reason not to.