Sure I am an old geezer. I retired 8 years ago.
Sometimes I am nasty on forums to school kids and most come from a single 3rd-world country and send me hundreds of PMs demanding me to design circuits for the lazy ****.
I don't use smileys here because there is no smiley button like there is on other forums and I forget is it is a (
or a
).
The TDA2822 power amp has a typical supply hum rejection of 30dB which is pretty good.
As I said before, your hum comes from the base bias resistors on your transistors and the divider for the opamp all of which do not have any decoupling.