Seems like you are an audiophile and for the most part htc investing heavily in that won't make much of a different in sales compared to lets say investing in a camera and a software engineering crew that knows what the hell they're doing to create a wonderful camera experience. So htc really needs to focus on a unique design, camera performance, a smooth sense experience and they still need that one added feature/service that enhances the user experience. So basically anything that can get the mainstream media talking all positive things about htc.
At the same time though, it may be little too late no matter what since the s7/s7e is already out, which I must say is a fantastic device(I currently have the s7e) with lots of great features, great camera, and great battery life then there is the lg g5 which should be out before the m10 as well which has a lot of unique features.