Just to clear this, this sounds are NOT S.A.2, and I think the switch velocity, is up to the touch of the player, anyone can experience that with any brand and model in either way(good or bad).
The S.A.2 enable the 2 switches next to the pitch and modulation wheel.
Not all the sounds on the T3 are S.A.2, there are also S.A.(1st Generation like in the T2), plus the Mega, Sweet, Live, etc. sounds in the instrument.
So far, the only other S.A.2 voices that you can add to the T3, is the Trombone S.A.2 and the Pan Flute S.A.2, if you notice in the link below, the other available sounds are NOT S.A.2.
http://music-tyros.com/# I do agree, the demo is not the best, then I have seen and heard a demo in the Atalier largest model that I wonder, some players can make a fine instrument sound like &%$#@, And it does not matter how good is the tone generation or resources the instrument has.
I am sure all of us at one time or another have witness that.
Most keyboards have a control or different ways to customize the players touch to the action of the key bed, and is evident that the player that made the demo probably did not prepare the most suitable music to show off the new sounds and the velocity switch was not properly adjusted.
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mdorantes