I have had the e2 and now have the e4. Im sitting in a car right now (otw to airport so on the highway) on my laptop and i tell you what. Isolation just seems better to me on the e4. Maybe its the insert or something. However the cable is alittle thinner on the 4's then the 2's. There seems to be less microphonics with this setup then the e2, however im not moving around...just tapping the cord to test.
Now, ive only had these for about 2 hours...however, havent taken them out since i slapped on the insert.
The sound is really quite different. The E2 bass is alittle shy, but its for sure NO clear once your hear these. There is almost a richness to it, but you can for sure tell that the e4 bass is clearly better. I say better, not bigger.
What really threw me was the soundstage on the e4. Its not like the e2 where the sound seems to be beamed directly into your head. It almost feels like a decent earbud or clipons, the soundstage i mean.
Hi's have more clarity. Mids , well...much better mid response imo. I actually dont have to EQ the mid out to keep it clean (had to do this on my e2, or it would sound kinda hollow). The lows are completely different. The e2 seems to have more bass, but its no where as clean as the e4. At times i do find the e4 alittle tin-ny sounding.
All in all...honeslty...the e2 fit me better...i guess cause of the fatness of the housing and all. The e4 fit fine, just alittle looser then the e2s did.
Am i happy with them over the e2? No doubt...the tight bass, clean hi's and above par mid make it a better sounding IEM.
Are they worth the money difference? Depends...if you buy the e2 full price (99$) and the e4 for full price (299). Then i would say no, its not worth the 200$ difference. However if you search around the web and find the e4 for like 160$ (ttvj.com) then yes the extra money is worth it. I say no more then 100$ difference i would pay. Anything more then that, you better off saving your money and buying customs later on down the road. Mod your e2s (kramer is a genius, cause he is asian, like muh) and it will bring out the hi's, unmask them if you will.
This is just my thoughts...take it as you will.....Of course everyones ears are different, so sound might not be the same for you =)
This is just the condensed version atm. Im going on a small get-away till sunday, so i will have about 3-4 hours worth of flight to really test these out. I even brought my Go-Vibe with me, so i have a amp to test it with.