I have this problem too. I have Asus Xonar Phoebus and bass I can hear only when I switch Tiamat to stereo mode. When I us onboard - Realtek soundchip, i can manage this with switch on bass enhancement. But this Xonar Phoebus software does not have such option. On ROG website I found that there should be "Flexbass" option but it is not. It looks that i need to get rid of this Asus Soundcard. Or is there some solution? Thank you.