The members of the Rembrandt Chamber Players had been performing on an ad hoc basis for years before deciding to start a concert series in 1990, which has been a boon to chamber music aficionados. Because of the Rembrandt's unusual instrumental configuration--flute (Sandra Morgan), violin (Sharon Polifrone), oboe (Robert Morgan), cello (Barbara Haffner), keyboard (David Schrader)--many nonstandard works in the extensive chamber repertoire are theirs to revive and popularize. And these veterans of the local music scene seem to have gathered a following with this approach; their first CD, 20th-Century Baroque: Modern Reflections of Old Instruments, produced by the local independent label Cedille Records, is doing quite well for such a relatively unknown group. The Rembrandt's latest concerts are noteworthy not only because of the refreshing program but because they also feature soprano Linda Mabbs, a well-regarded alumna of Music of the Baroque who now lives on the east coast and returns only occasionally. In this concert she will sing three arias by Handel, a specialty of hers. Then, with Robert Morgan, Keith Conant on viola, and Haffner, she will perform Hindemith's 1924 cantata Die Serenaden. Also scheduled: Schumann's Three Romances for oboe and piano and Bach's peppy "Trio Sonata" for flute, violin, cello, and harpsichord from The Musical Offering. Sunday, 7.30 PM, concert hall, DePaul University, 800 W. Belden. Thursday, March 4, 7:30 PM, Lutkin Hall, Northwestern University, 700 University, Evanston. 708-328-2492.