Toshiba A100 sound line out/headphones out problem - low bass.

When I connect headphones out (mini jack to 2 rca) to my stereo amplifier line ins, bass sounds is very bad, e.g no drum bass/kicks sounds at all. The sound, if you listen on headphones alone is excellent, but the problems starts when you are trying to make the sound play on your stereo sound system.I tried to adjust the virtual sound HD realtek configurations etc, and still very bad bass sounds. The only way I can hear the drum bass sounds from a music is by putting the circle surround xtract on mono mode (from the Toshiba virtual sound settings, but then I have the feeling that the sound is not a real stereo sound, I have also disabled the HD realtek equalizer and so on, nothing has change, I tried to put off Toshiba virtual sound also, but still no drum bass/kick sounds. This is very frustrating, as this is for work. I do not have an external usb soundcard etc, as I know the line outs from the sound card will provide the best sounds. The headphones out is not a real line out as far as I know (different voltage/impedance etc) and was meant for headphones only but most people use it as a line out to connect to their sound amplifier. I think this is a serious probem and Toshiba should really look into the matter. I know many people who are frustrated by the same problem with the Toshiba A100 laptops.Will appreciate your help.