Somewhere on the net there is a sound clip of Jay Ungar telling how he came to write the tune, and he said A-sho'-ken. From memory Ashoken is the venue for a yearly music camp. Having written the tune, Ungar then didn't do anything with it for several years, because of the memories it evoked of striking camp.

Spaw,I managed to avoid that pronunciation becoming necessary, by luring some other guy into saying the word before I dared try it *G*.

And phy-on is a bit over-elaborate Sorcha - plain fin will do - as in Fin McCool (Fionn McComhaill), Leader of the Fianna.

Going back to Ashoken, no wonder the tune's taken off - I read somewhere that it got a staggering 11 hours of play during the Ken Burns Civil War series.