it's not the makers of the dvd players (sony, pioneer etc.) that are at fault, it's the disc manufacturers. let me put it this way........if it was a problem with the machines then all dvd discs should have at least some problems with lip sync , but thats not the case, its only a select few discs.
i have a pioneer 515 and haven't experienced major problems with it anyway!
thats my 2 cents worth.

G.D