powering TPA3116 with 24V - how much ampere

Thanks. should I take any margin? (although I will not drive the speaker to it maximum power as it will be probably to loud)

Regarding the input connection to the amplifiers. I'm using balanced mono output from my audio interface. what cables should I use? can I use unbalanced TS cable?
Take some margin, not really obligatory.
It depends on whether the power supply is switching or linear.
Additional filtering capacitors of good capacity are mandatory on linear power supplies.
Switching power supplies are naturally filtered and regulated (except exceptions) and withstand overcurrent peaks over a short period of time.
For the wiring if it's not hi-fi... you can wire the ground and the red signal of your balanced cable only, there will be a loss of gain... But if your source is relatively high in voltage.. it should be fine.

We can also put the white signal - to ground, I don't really like that... this amounts to short-circuiting an output of the op amp.
There are also conversion circuits or signal transformers...
The choice depends on your requirement.
I'm gonna get this 24V 500W PSU
Shall I add filtering capacitor for this PSU?

I decided to use this audio interface which have only unbalanced RCA output.
So I guess I will use female orca socket at the amplifier box input.

I'm gonna build the amplifier box from 4mm wood. shall I child the box using shielding tape such as this one?

Is there any quite 12v fan from Aliexpress you can recommend?