[r91085]

I got a power cable which includes ac noise filter function.
I use it on sta-9 and sound seems has some difference.

The sound seems become a little clean or remove something in music . I am not very sure what kind of difference is it .

But I feel the origin power cable sound better than new one with ac noise filter function even if mabye it got some nosie from power .

Dose sta-9 need another ac noise filter work with it ?

[rustydoglim]

Impossible to answer this kind of question.  The issue is your power line, which has nothing to do with STA-9. Sure, if your power line is very noisy, you would be better off with an AC noise filter.