Check out this link http://hamiltondesign-consulting.com/Cus_ctrl.html
It does pretty much what you want in principle. For absolute db levels check out http://members.lycos.co.uk/sgctek/
Check out this link http://hamiltondesign-consulting.com/Cus_ctrl.html
It does pretty much what you want in principle. For absolute db levels check out http://members.lycos.co.uk/sgctek/