I've only heard the combo once, because one of my employees owned a set of LS3/5as. We ran them on our S-30. The speaker is an effortless load (16 ohms) so it is very tube friendly. I remember being quite surprised at how well they did bass. And the rest of the range was fine. the S-30 is as big an amp as you want to put on them; the LS3/5s don't take a lot of power.
Have fun!