The GT's plinth is aluminum. No difference in sound between the two, as I can detect.
And yes, yes, yes, Samtse, if you have a reference already or know its sound, then you must have an Amadeus.
(No kidding)
And yes, I don't care for the name, and yes, the golf ball is great for silly punsters to amuse themselves--I don't even see it in my mind's eye while I'm cueing, but the joke will be on them when they hear it--compared to theirs!
Take care.