Different size caps in psu

Hi Thanks for reading In my topping PA5 II amplifier smps power supply there are 5 caps on the secondary side. Four are 470uf and one is 47uf
Why is this, why the different sized caps. In some psu people put small film caps on the underside of the big electrolytic caps and report an increase in treble
Is this something that topping are doing with the addition of the 47uf cap, perhaps to help give a flatter response
Would it be worthwhile doing something similar to the primary caps, put a small cap across them, i have a few 10uf 450v that may be suitable ?