ok . found solution for this.
First i need to somehow mesure the real output of soundcard. And i found it's not exactly 192000Hz.
It's ~192014. so that explane why output buffer after some time expires.
so because my input for ST comes from VAC i try to put 192014 in VAC.. but with no succes.
In front of my eyes was CLOCK Correction in VAC
i did't see it at first time ... then i start to play with it.
Than i found number 100,006% tune out with soundcard wich have ~192014Hz on output.
Thanx Hans for point me in for this.