I pair M9 with neutral source as of now im leaning toward ipod touch 7th. Ive had it with n6ii but im still favoring M9 with ipod touch 7th for its clean and neutral and also it brings up the vocals better. I do sometimes raised a couple dBs on 2khz region to increase the pinna gain. But that's it. Easy with clean source as of ipod touch 7th is fast and thin. VX is excellent. It could do anything you throw at it. However, something is missing. It could be the boosted bass. Or the lack of warmth in vocals. Or the dipped at the highs. With that combo, it sounds emotion-less to me. Artificial. Ive tried multiple tips with VX. Azla, Symbio W, spiral dot, etc. The best i could get is symbio W with the foam. It tames the bass a lil bit the overall signature is still artificial to me unfortunately.