Modular DAQ for Push-to-Talk Audio Control, USB/Serial, 5V/9V Powered Recommendations

Designing up a box that basically needs to play audio from a PC while a Push-to-Talk switch is depressed and shut off the audio signal when the switch is released. The Audio signal is carried on a separate line from the Push-To-Talk voltage.)It needs to be modular (as not in a circuit card installed in the PC). Ideally powered from either 9 or 5 VDC. It also needs to communicate through either a serial Comm Port or USB etc...to provide the change in state detection from the PTT button.
What is the best Digital Acquisition Module for this application?   

There's a line of ICs ISD25xx that are a bit old now but may make your job a lot easier.  They are designed to record and playback single or multiple (user selectable) messages, retain messages with power off, and have versions doing anything form 60 to 120 seconds (they are cascadable).They can be pre-recorded and then used in playback only applications like yours.I'm not sure these will do what you want but they'd be worth a look. I'm not sure if they're still in production but they're certainly available.  I have a few SMD ones around somewhere.

Hi Alexander-I agree with David.  Those parts are still available.  You can also find them in recordable greeting cards.  The company that makes them has changed hands several times in the last few years.  Try doing a search on "Chipcorder".-Rick