Sony's SACD players need at least 400 hours on
each laser to fully burn in completely. I've been doing 12 hour night time runs myself for the past month to burn in the CD laser on my 9000ES...and I haven't even gotten to the SACD/DVD laser yet.

That's 800 hours total to burn in the player. Also keep in mind there's supposedly a stage during burn in where Sony's SACD players will actually begin to sound
worse, around 100-150 hours, and then rise back up to sound better and better. There may not be much of a difference between your XB940ES and the 777ES in CD playback, given they're both from the ES lineup. On the other hand, I heard a pretty dramatic difference between my 9000ES and the SCD-1 in CD playback in that the SCD-1 was MUCH more revealing and portrayed treble much crisper and clearer (which in turn gives it a drier midrange compared to the 9000, which sounds warmer and more musical...some would call the 9000 the more timbrely accurate player and possibly
better than the 777ES if you look over at Audioasylum), so there should still be a difference between the players.