Today I'm sudden noticed the right side is louder. To determine the problem was HE-500 or WA7, I have tested with Icon HDP and used the USB mode of WA7 ==> the problem is WA7
I also try to test with some IEMs, the problem present with IEM slightly less than full can.
Have anyone experience this issue with WA7 or other amp? Is it normal or I should return for warranty?
Current I have to change the soundcard balance setting to 100 for the Left and 80 for the Right
It's not normal.
Once the tubes have cool down, do switch the tubes and check whether the left side now become louder or still the right side louder.
If the left side now louder, could be one of your tube is failing.
If still the right side louder, maybe send them back for warranty purpose if your still can't trouble-shoot the problem