I will receive those cans soon and I haven't found much picture of the actual stuffing trick. I would very much have some more information about it. What did you use? Cotton? Is it easy?   Tanks for your replies.

Just got the answer from MP4 Nation :     Quote:   However I don't agree with them. On my set, If I let the holes opened, I can't get a good seal and thus I have virtually no bass (compared to closed holes).   I guess I should just return them but I'm quite lazy :)

Quote:  Did that... I'm waiting... During that time I chose to do a whole day with the front facing pinhole sealed for both buds and I quite like it like that actually. It's not that bassy...

Indeed it's not just you!   Does anybody know if these holes are supposed to be closed or opened out of the box?   About returning them, the only difference I will have with the second set is that both buds will have the pinhole sealed or opened. I can do that myself with the current set...

I just bought some M5 IEM from Amazon and I've got the same problem as Calroth.   When I received them, one bud had the "front facing pinhole" blocked and the other one was opened. It was really strange since one of the earbud seemed to "fit" better. It took quite some time for me to realize...