Pat, there are sometimes concerts at the San Isidro cathedral. The Auditorio Belgrano - not too far from you - has a series of concerts. I suggest you send an email, in Spanish, to the following asking that you be placed on the mailing list. You will get a lot of information about musical life here. Here is the email:
You´re welcome. There is a LOT of music around town. DOn´t limit yourself to San Isidro area. There are free concerts at the UBA law school and virtually free concerts at the Belgrano Auditorium among othert locations.