GIven that you haven't used any descriptors of the noise, it's impossible to say that it's gear noise over bearing over small end bushing.
A video would solve this issue.
I've never found a set of E50 gears that were sloppy enough to howl. Chipped teeth? Sure, never loud enough to hear over a kitted bike.
I am going to put money on bearing howl and/or small end brass bushing galling.