Thanks Will. Got it. Just changing the extension from .m4a to .mp3 does the trick without having to actually convert anything.
It’s a nice time saver for me over the track by track process I had been doing. Slick!
Only other issue I've noticed is that the volume button doesn’t really seem to work (I’m using Safari on OS 10.12). The icon opens to two additional speaker icons but clicking on either doesn’t seem to do anything.
Since the Stack settings refer to a color for the Volume Bar I had assumed that clicking on the Volume icon would bring up a slider?
But it’s not a big problem for me. Just curious if this is a bug or something I’m doing wrong.
Thanks again for the quick response.