Mad dogs and music lovers ventured out in the noonday sun (to paraphrase Noel Coward) for the Philadelphia Virtuosi on Sunday, but with sensible rewards. Though snowstorms bring out the best in the Philadelphia Orchestra, the heat wave did the same for this chamber orchestra, which performed in the un-air-conditioned sanctuary of First Presbyterian Church and later migrated into the church's pleasant, cooler back room.

The orchestra had just ended a tour of smaller communities in Illinois and Texas, and was in particularly good shape in a program of string- orchestra music that included Tchaikovsky's

Souvenir de Florence

. Exterior polish was wanting, but there were none of the periodic implosions that have been heard in the past, and principal players were not only hugely capable but hugely inspired.

Music director Daniel Spalding has a laudable commitment to neglected repertoire, even though I haven't summoned much excitement for his Naxos-label discs of music by Howard Hanson and George Antheil. Not so with Spalding's latest discovery, Philadelphia-born Vittorio Giannini (1903-1966), who was forgotten quickly and completely despite successful opera versions of

The Scarlet Letter

and

The Taming of the Shrew

.

Giannini's 1946

Concerto Grosso

, heard Sunday, drew on the neoclassical manner of Stravinsky, and more significantly, Ernest Bloch, with clean, chic surfaces, syncopated hiccups, harmonic resolutions that were ingenious. The piece's mastery of its genre eclipsed even its antecedents. The first movement's development section was a bit puny, but the composer delivered ample compensation in the searching slow movement.

The Tchaikovsky

Souvenir

was given a performance that honored the music's tunes but didn't depend on them. Harmonic dissonances made intrusions more pointed than usual, almost like a depressive episode, establishing a darker undertone that never quite left and giving the music a dimension that suggested this piece is, in its way, the equal of his symphonies.

Pianist Gabriela Imreh is usually the Philadelphia Virtuosi soloist, and though she has power-in-reserve fingers and romantic temperament best matched with Brahms, she played Bach's

Piano Concerto No. 1

on Sunday in a way that few dare in these days of historically responsible performance. Treble lines bristled with concentration; bass entrances, alone, felt like events. You could imagine the great Tatiana Nikolayeva (1924-1993) in our midst - a pianist whose approach came out of a grand 19th-century tradition and for whom Glenn Gould was a mere cul-de-sac (as he should be).

Contact music critic David Patrick Stearns at dstearns@phillynews.com.