@Clintgm, i'll try your suggestions, they make sense. i didn't find any setting in the monitor sw to turn on/off sound, just sound level and it was at (0).
i re-visit the NVida controls. quite easy for me to miss something there.
i don't know about when the DP port is used the analog port would be disconnected, but it might. my speakers are connect to the analog out jack on the left side of this G75. but as you know Windows thinks the monitor is the default.
not such a big deal, just the slight inconvenience of switching that. thanks for your help, i'll give it a try