sounds ok. You could try 2.5 reeds before worrying about another mp as the 6 is not real open so a slightly harder reed might start to give you a bigger tone. Give the reeds a chance though, don’t just buy a box and give up if the first one sucks, try them all and then stick to the best feeling one and play it everyday to wear it in a bit or else you might never know.
I’m using the zz’s on the alto as well and they are pretty good right out of the box so when you get the good one it shouldn’t take long at all.
cheers
Johnny