Here is a blog of people discussing that. There is some interesting info that might help you. Sorry, I've never done this or would tell you a simple way, although these solutions seems easy enough:
http://www.avsforum.com/avs-vb/showthread.php?t=1053542
Here's some similar info:
http://www.hometheatershack.com/forums/system-setup-connection/1711-stupid-question-s-regarding-12v-trigger.html
Looks like the 12V adapter into a switched outlet is the easiest way, but there are other options.
Hope this helps, and good luck!

I hope i got your issue well. the option I can give you is to use a 12v wall wart or power supply plugged into the switched outlet on your amp. it should do the trick.

Regards

Hello,

I advice you see the information on the below link,

http://www.6moons.com/audioreviews/stello/stello.html

Type the above link on your web browser to see information therein.

Take care.