I'm suspecting my unit has a channel imbalance as I mentioned earlier, a little bit alcohol sanitizer probably got into the right unit (I was cleaning my eartips with them and didn't check if there was any in the bore, but once I pushed it in I think some got in!
). It's by no means dead but I feel it is a tad bit more laid-back than the left channel which feels a tad bit more sibilant (this is with mono tracks). I looked at the "dissection" in the other IM70/IM50 thread, and there is a long way between the nozzle and the driver so it's unlikely to be damaged.
Maybe it's just my mind playing tricks on me, as I felt the same thing when I bought the SHE3590, or maybe it's just there's something in my ear (though I did check other headphones I don't feel any problem with them).
As for wide-bore tips, I tried making stoppers by using the plastic rings taken from old comply tips. However, they stick out too much and the fit becomes somewhat inconsistent. I prefer the wide-bores pushed all the way in but it feels more loose than stock tips or SHE3590 tips.