I don't believe in burn-in for pmp's and iems.
Sound changes more 'in the brain' than 'in the ear' over time when you talk about 'burn in' over hours to your PMP or IEM.
I'm sure the SM3 din't change after the burn-in, neither did the bass lacking CK10, after listening to them for a few days I felt the CK10 had tight bass(another way of saying they din't have enuf sub-bass), even though lesser than my other gear, but thats quite enough bass there in the ck10 to make a Re0 or AKG k701/2 owner appreciate it and stand up and say, Holy SoundStage!!!.
So the only thing that changed after 100+ hrs of listening is only my opinion. I said, 'let the player burn-in' in an earlier post thinking wiser of the reader to interpret that 'let the sound sink in'. The process of letting the ear adjust to the change in the frequencies produced over-time(as compared to the previous PMP). The more you try different things(genres, pmps, iems,other items in the chain) the more you will like/dislike what your hearing and want to change things. I hope I made some sense concisely.