The piece started as usual, with that clarinet murmur and revolutionary smear to the top. But when Roberts entered with the first piano-alone section, he entered remix realm. Gershwin's material was referenced, sometimes obliquely, sometimes not at all. Slipping between two timescapes, Roberts seems afflicted with a minor case of genius, following leads to unlikely places, bringing in influences as amorphous as they are powerful. Was that a borrowing from Debussy, those right-hand whole tones against a walking bass? Chopin floated into some of the pianism at one point.
What made it all the more exhilarating was the presence of his sidemen, whose own layers lay naturally atop Gershwin's score and even enhanced the composer's ideas. Drummer Jason Marsalis slipped in sly hemiolas - syncopated patterns that play against the basic rhythm - and in general braced the ensemble. The amplification system didn't do Roberts any favors; one could only approximate an opinion of his tone.
For this penultimate series in his tenure as artistic director, Nero rounded out the program with more Gershwin: a Cuban Overture that was one or two café cubanos short of ideal verve; a truncated version of An American in Paris that started not with its usual light-step telegraph, but at the sexily loitering trumpet solo; and a Fauré-esque orchestra-plus-violin transcription by Nero of the second in the Three Preludes that benefited enormously from Michael Ludwig's sweet violin solo and a lovely soft pillow of a tuba part by Brian Brown.
Two pianos nestled on stage when Nero and Roberts exchanged thoughts. In "Someone to Watch Over Me," one tossed out an idea and the other ran with it. More beguiling were those moments when the improv was so intrepid and full of flashing cultural connotations that you couldn't be sure who was playing what.
Contact Peter Dobrin at 215-854-5611 or firstname.lastname@example.org. Read his blog at www.philly.com/artswatch.