Turning an external amplifier on or off when audio is played

Hello,

I'm working with an embedded system that uses the SGTL5000 to play audio. We have an amplifier connected to the DAC output, which we can turn off using a GPIO pin. I'd like to automatically enable the amplifier before playing a sound and disable it after playback has completed. Are there any hooks that would allow me to do that in userspace? If not, is there something in kernel-space that would allow me to accomplish this?

Thanks,

Amr