Need a Amp with Volume Control

Where did you get this info from?

According to the manual (http://www.docs.sony.com/release/KDL40S4100.pdf) the output volume is fix.

I also couldn't find any setting in the menu to change that :(

Please let me know if I'm missing something

I just did a search for your model tv and found a picture of the rear panel. It showed fixed, variable and toslink. I'm pretty sure its the right model but here's a link to the picture. https://www.google.com/search?q=Sony+KDL+40S-4100&client=ubuntu&hs=Rxr&channel=fs&source=lnms&tbm=isch&sa=X&ei=KBdPUuLEDoW4qAG0voCoAQ&ved=0CAkQ_AUoAQ&biw=1366&bih=625&dpr=1#facrc=_&imgdii=_&imgrc=sAzJWWFxaQdwIM%3A%3BlS3KV_gTAZen_M%3Bhttp%253A%252F%252Fswotti.starmedia.com%252Ftmp%252Fswotti%252FcacheA2RSLTQWCZQXMDA%253DVGVJAG5VBG9NES1UDG%253D%253D%252FimgSony%252520Bravia%252520KDL-40S41004.jpg%3Bhttp%253A%252F%252Fswotti.starmedia.com%252Ftv%252Fsony-bravia-kdl_40s4100_17326.htm%3B1000%3B639

Zd542 is wrong, even the picture he provided in a search shows only "fix". Also, the manual states fixed with no option to change.

Sorry for trying to help.

Zd, sorry for being so blunt with my post, but when you keep providing the same incorrect information, it is definitely not helpful.