Customise the URL for an asset I need to prepend a URL to the beginning of an asset URL in order to track stats for a podcast via Blubrry.

What are the options?

Specifically I need to drop the https that would appear in my URL by default.
This doesn't work with Blubrry specifically, but you can use it to get the data into Google Analytics for things that aren't normally trackable: Instant Analytics

Check out the Tracking RSS Feeds section.