Volume regulator, and switcher

Hi guys, I'm a new user here and my english is not that good, by the way, this is my question. I need something to regulate my headphone volume, so I don't need to regulate it from windows, but I don't know what I can use. Than, I have a 5.1 system in my pc, and everytime I want to switch from headphone to 5.1 I have to change 3.5 jack. So I need something like a "switcher"? or something, so I can switch manually and easily from headphone to 5.1 without remove any 3.5 jack. I don't know which device I can use to make it. I made a screenshoot if you did not understand it. Thanks.