I think it’s a great idea to focus on listening input when learning languages. It’s the way I learn languages and it really is vastly more effective than traditional classroom methods. If you’re a relative beginner or intermediate, I would suggest any material that allowed you to follow the transcript, looking up unknown words etc a few times before downloading the audio and listening to while walking, taking the subway, or whatever, perhaps even eventually coming back to the same lesson twenty times or more.
An app to possibly consider, along with the suggestions made by other people above, might be lingq.com In particular I would recommend its mini stories series which is comprised of 60 stories, each approx 3-5 minutes long. The downside of lingq is that if you are focusing on traditional rather than simplified characters the traditional characters can only be shown above the simplified ones rather than being able to toggle between the two.