There are many frequencies available in the world. Currently, most American musicians use the standard pitch (A=440Hz) for the tuning, but that does not apply to everyone in the world especially other than Rock/Commercial music, I believe.
Many classical orchestras tune higher like 442Hz to 445Hz, and guys like John Lennon & Paul McCartney have tuned their instruments to C5=528Hz (A=444Hz) in some of their songs (Paul started recording songs in 444Hz/528Hz after 1999).
There are some discussions and theories about C5=528Hz (I'm not going to talk about it here though), and of course I was just curious to check it out :)
So, we started playing our songs in A=444Hz. It is pretty easy to do so (you can change your standard pitch in your tuner and your synthesizers), and… it is just…. amazing difference!
I thought it would not be that much difference between 440Hz and 444Hz…. just 4Hz! But that 4Hz difference actually gives really driving & clear & exciting sound I have never experienced before.
Surprisingly, I don't feel much tired after practicing several hours, and I really enjoy playing our songs more and more. It is really interesting…. and I like it a lot :)