Your TV may have video and audio in sync, but that sync will change just by moving
your chair closer or farther away. Audio can lag video by quite a lot
without being noticeable. Leading, not so much. Some video players (like
VLC) have a control to move the timing of the audio with respect to the
video. in this case, just changing the buffer size in jack will add more
delay. I think what you really want to know is if there will be a
noticeable difference between when the person on screen moves their lips
and their voice happens