Joined the RE-400 bandwagon recently, and liked them so much I have RE-600 V2s on the way (did HiFiMAN have a Black Friday sale?) The small white tube tips work best for me out of the stock tips, but once again JVC Spiral Dots are the winners of the day for me. On the RE-400, I will say that they didn't help the bass at all - perhaps they even reduced the limited amount of what was already there. However, they seemed to completely remove the grain from the sound for me, adding some clarity without any of the harshness. I think they'll be a great fit with the RE-600 based on what I've read.