Thanks for the feedback!
This option is already in progress but it is still months out. We are working to allow this support from within the Tithe.ly Dashboard as well as from any external feed. This sort of support adds much more complexity than if we simply locked it down to only working from our dashboard, but our hope is that it allows churches much more freedom to host their audio sermon feeds however they want.
Please let me know if there is any more information that I can get for you.