This radio interview is well worth a listen if you are interested in the benefits of modern digital hearing aids, their limitation and how they function in conjunction with a hearing loop.
American Composer Richard Einhorn talks his experiences and extols the virtues of Hearing Loops on NPR Radio.
http://www.npr.org/blogs/health/2013/04/08/176225511/listen-up-to-smarter-smaller-hearing-aids