The fragment is reported by the tradition as:
Ἦρος ἄγγελος ἱμερόφωνος ἀήδων
Or sometimes with ἡμερόφωνος. It would seem we just need to fix a psilosis for the third word. However, Edmonds and safopoemas amend the last word to ἀήδω, and Lobel-Page and Campbell put all but the first word in cruces, with Lobel-Page adding «Aut ἀήδω aut ἄγγελον ἰμερόφωνον scribendum», as if the accusative was the only form in -nu. Voigt says that is "praeter necessitatem". So, what gives?
What reasons do we have to amend or to not amend this?