Feature used when recording to a tape that extends high frequency range of cassettes and increases high frequency headroom by adjusting tape bias. Bias adds a high frequency signal to a recorded tape to help dissipate distortion. The distortions are recorded into the high frequency bias, which is inaudible to human hearing. However, high frequency signals recorded on a tape can bump up against the bias or otherwise be affected by it resulting in a lack of high frequency information and range. Dolby HX Pro reduces the bias during times of recording high frequencies so that there is more of a buffer between the high frequency signals and the bias resulting in better high frequency response.