Thanks for the follow-ups here.
So sorry. I don’t have any personal experience with the apps you mentioned. However, here are some general suggestions that might help in some cases, or perhaps spawn new ideas for you.
1. Instead of using Remote Authentication (i.e. HTTP header authorization); you could provide your members with links to download files, which include a File Download Key in the link itself (which provides the authentication). This will avoid the need to use Remote Authentication in most cases. While it’s not always practical to go this route, in many cases it does fit the bill. You can learn more about this from your Dashboard.
See: Dashboard -› s2Member® -› Download Options -› Advanced Download Restrictions
For instance, if you have the ability to generate a podcast feed dynamically (i.e. with PHP), you could build links that include File Download Keys for each MP3 file that will be available in your feed.
2. Some apps (like iTunes as one example), will be capable of working around potential issues with HTTP authentication, if you place your XML feed file itself, inside a location that requires HTTP authentication. In other words, make your XML feed manually, and then place it inside of the /s2member-files/ directory. Provide users with a File Download link for the XML feed, which requires Remote Authentication (i.e. HTTP Authentication). In this way, if the feed itself requires HTTP authentication, the client application might be able to handle HTTP authentication on the feed, and then NOT need to handle it for each MP3 file available within the feed. It just depends on the app though.
See also, this video: Video » s2Member® File Downloads (Remote Auth/Podcasting)
3. Another possibility is to build a mobile app of your own. A custom app might be built in a way that interacts with s2Member’s ability to produce File Download Keys, as I mentioned in #1 above.