I think it will have enough power, the S5 is not very difficult to drive. Much less than Q1, Q5 and even S1. But I also think there are other amps which sound better (and I owned a Devialet D-Premier, that I used with both S1 and Q1).
Is it a good amp for its price? yes, very good.
will it be the limiting factor in your system? yes. Not because it is a bad amp, but because the S5 is so transparent that you hear better upstream components.
But you can always go for it, and upgrade it in a few years
PS: I personally think that the SAM is more marketing than anything else