Well, I have been AB testing the ER4P and Atrio M5 for 15 minutes, using a two-pronged plug from my Creative Vision M headphone jack (no amp, EQ off and no bass boost, which the CVM offers). And I have to say, I like them both, even though they are very different. I have no real technical knowledge, I just like quality sound, and it seems to me the Etys and the M5s are different animals, but who says you have to favor the beauty of a tiger over the grace of a Cheetah? So I can deliver any technical reasons why I feel they are both keepers. I do find the Etys easier to insert (using the Comply short foamies, which are a great match with the ER4Ps), but I am waiting on a set of the new Shure black foamies for the M5s. I also will try out a pair of the Comply tips on the M5s as well. Makes sense they will work.
So my admittedly limited technical expertise aside, I find both products worth keeping. That may seem odd, and maybe long-term one will win out over the other. But for now, I can't part with either. Though I have to say, the longer I hear that amazingly tight, bold bass line on Black Cow by Steely Dan rumbling as I type, the M5s are really starting to grow on me. When I switch over to the Etys, the Steely Dan clarity is apparent, but the base seems so far away (without the boost turned on). Hmmm. Could be a portent of things to come.
Anyway, that's my humble comparison. Not much of a decision, I suppose. But I really do like the M5s, and can't wait for those new tips to arrive.
Oh, did I mention I also ordered a pair of Crossroads MylarOne X3s as well (on their way)? Have to see how they stack up. If not much different than the M5s, then one of them will have to go. Or not. Doh!
This place is gonna make me nuts.