Error Using Audio plugin

Answered my own question. Kept here for others who may have in the same problem.

Turns out, being locally hosted WAS relevant. the problem is line 192 in /wp-content/plugins/audio/js/audio.js

swfPath: 'http://' + window.location.host + '/wp-content/plugins/audio/js/',

This expects the site to be based at the root /, as mine was in a folder I just changed it to:

swfPath: 'http://' + window.location.host + 'MY_SITE/wp-content/plugins/audio/js/',

and we’re away.

Remember: revert to original line when moving to production.