We must have different definitions of dark, as I don't consider bassiness a prereq for darkness. I'd hate to think of what your opinion is on the Etys if you find the minor measured 2k bump to add plastickiness. I really don't hear the 2k bump (despite the plots) probably because it's being swamped by the rest of the darkness.

Added aggressiveness? The RE400 doesn't seem to have enough attack (dynamic capability) to be called aggressive. I would say orchestral and acoustic sounds poor on the RE400 for that exact reason.

My Tenore developed a channel imbalance in the past month that's gotten much worse. It's basically unusable now unless one EQs in balance (not worth it to me). 

RE400 is kind of two-dimensional compared with ER4S. But I prefer it because it's comfortable and less fatiguing. (ER4S with orange filters are roughly the same degree of fatigue; PM me if you want some). I wouldn't characterize RE400 as either dark or bright but it's definitely warm-toned and not cool-toned, presumably because of the linear bass together with the treble roll off. I happen to like it and actually want it a little darker so I ordered RE600.

I'll stick with my original judgement about both: neither makes the cut.

My Tenore developed a channel imbalance in the past month that's gotten much worse. It's basically unusable now unless one EQs in balance (not worth it to me). 

RE400 is kind of two-dimensional compared with ER4S. But I prefer it because it's comfortable and less fatiguing. (ER4S with orange filters are roughly the same degree of fatigue; PM me if you want some). I wouldn't characterize RE400 as either dark or bright but it's definitely warm-toned and not cool-toned, presumably because of the linear bass together with the treble roll off. I happen to like it and actually want it a little darker so I ordered RE600.

I'll stick with my original judgement about both: neither makes the cut.

There is a fix for the channel imbalance. There is a metal plate behind the nozzle mesh that has a very small opening. Apparently moisture can build up there and cause the imbalance. Several users have found that if your replace the mesh screen with a small amount of cotton wool, it permanently gets rid of the imbalance.

New iem for consideration at $100, the Thinksound Rain2. Take one home, it's pretty nice for a hundred dollar earphone. Slightly warm, good timbre, extends well below, treble is present but non-ear-ice-pick-y, bro. Detail is reasonable but not phenomenal, soundstage is good, it's made of wood.

Speaking of which, there's a 25% discount for all models at their store.