Still using Windows Mobile on your HTC HD2? And if your HTC Audio Booster is not the latest version 2.5. Here is the time for you to upgrade it. I believe latest HTC HD2 ROM should have it. As I know, Energy ROM that I am using months ago has it already. But I did not enable it until now. 😛
Download HTC Audio Booster v2.5 for Windows Mobile here.