120V or 240V

Whether they will work better one way or the other is something I can not address. (The obvious answer to that is to ask the manufacturer if one way or the other is better.)

However, if you are bringing this to the USA, then the resale value of a 240V unit will probably be less here in the states, because most people do not have 240V outlets in their stereo rooms.
(I certainly don't.)
So, if you want to sell it for top dollar, you would probably have to sell it to someone in a country that has 240V, which means shipping out of the USA. (I don't know about you, but that is something I don't like to do).

Something to think about.
Good Luck with your decision!

The obvious answer to that is to ask the manufacturer if one way or the other is better.

I agree with Kurt tank......
Something else to think about, after market power cords. You can not use a standard NEMA 5-15R or a 5-20R 120 V receptacle on a 240V branch circuit.

If you are in USA, I recommend getting it set for 120V. This will make resale (which imo, is smart to consider) much much easier. I know of some real great amp deals at the moment, but they are "shelf-huggers" due to the fact that they are 220V models. If the were only 120, they would have sold in a day.
I see no sonic benefit to a SS state amp running on 220, since the voltage must be stepped down to the same voltage for the boards,(the 220 amp has the same everything except the transformer) so it does not really matter what the line V is.

PS. How do you know about SL ? How would you rank them with other brands that are better known in the US ?

I have a local dealer that can get that brand, but with no floor samples, I would never take a chance but I almost did.