In version 1.85, the surround sound check box changes to headphone virtualization in the HD audio manager control panel when headphones are plugged in, but the frequency response is unchanged. And for v1.85 drivers, plugging in headphones has NO effect on the frequency response, even though the drivers know headphones are plugged in. However, the full-range speakers check box has NO effect on the frequency response. The blue curve should be the frequency response for full-range speakers or headphones. In both images, the red curve should be the frequency response for limited range laptop speakers. The second image is for the Realtek v1.85 drivers.
The first image below is the frequency response for Toshiba's OEM version of the Realtek v1.60 drivers. If your Windows Vista Realtek HD audio codec has poor bass response, the following information may be useful.
