In a message dated 98-10-23 22:01:02 EDT, you write:

<< Could you tell me the simplest way to control the AC signal? I mean I
 want to switch the signal on or off with a I/O pin form my PIC. The
 signal is kind of voice or low frequency. By the way, a solution with a
 relay is not expected, there must be other ways....
  >>
National Semi LM4862N is a 350 mw amp with a mute input that works great.

Max