[Q] Setting Volume Control topic

Hey guys,

i was looking for this, but found no matches yet. Hope its not a double, but i definitively need ya help.

I bought myself a Gigaset QV 1030 tablet, with Android 4.2* on it.
I enjoy this tablet in almost every situation with only one exception: The volume is too loud.

There are many apps out here for volume control. But since most of them just work in greater steps like 10%, 20%.. I'd like to set the Volume Control myself, either in shell, or as app.

But does anyone of you know the command therefor?


PS: Im still looking for somewhat like an API-Catalog for Android, is there such thing?
PPS: This is a repost of the original one. Just located former post in the wrong section. I Hope I am right here ;)

Thanks already for any help.
Best Regards
Jan