Wow, I exchange a nice convo with a fellow head-fi'er and mention I thought the ER4S's highs sounded a bit muffled. He found that odd and I later concluded the placement of the spike probably just took away from the rest of the high end, causing me to focus inadvertently on the vocals when I wanted to hear the cymbals. These guys sounded smooth at the top like the ety's but I didn't notice the same problem. I'm going to try that same song again with these bad boys and see if it sounds similar but memory's a bad little muffin.
with correct insertion depth the treble peak should be above 12kHz so it shouldn't be a problem.