Have you tried burning in the AM-90s?

Newbie here, very similar situation to yours though, so I'm curious what you decide on. I had a pair of Brainwavz M2 until the left channel got flaky after 6 months. Did warranty, then new pair had a side go kaput after almost a year. Gojira sounds phenomenal on my M2s compared to my old...

I listen to a range of music that includes classical, rock, alternative and heavy metal. I was blown away by how much better the M2 buds were compared to my old Sennheiser CX300.    Unfortunately, the signal in the left channel got flaky after 6 months. I went through the warranty process...

I tried both ways, in front with the wire under my chin, and in back with the wire resting on my neck. Same result, weight of the cord would pull on the right first. Not only is it annoying to have it fall out, but I also didn't like the feeling of more weight in one ear vs the other.

I had a pair Sennheiser CX300 earbuds that had a j-cord. While walking, the weight of the entire cord was on the earbud in my right ear, and it would frequently fall out. Now I have a Y cord, and the weight is evenly distributed to both ears, and they stay in place.