i always like my Pi 4 T the way they are, they sound so wonderful, a friend has given me a pair of NOS Coral H30 Horn Tweeter so i tried them on the pi four with a 4.7 uf cap, i can't hear the different initially, but after a while i realize the music has actually sweeten. at us 70.00 a pair i think it is o.kthis is the link to the tweeter
http://diyparadise.com/drivers.html
zeno