I have a Altec Lansing ADA-995 Dolby Digital 5.1 speaker system hooked up to my TV. I had to use the Optical Digital Audio out, a Digital to Analog converter, and a RCA to 3.5mm converter to get the speakers to work with my TV. Unfortunately, it doesn't allow me to adjust the volume through anything on the TV or TV menus. What could I install that would allow me to be able to adjust the volume?