Just got my pair of ER4S yesterday. I am very impressed with them. I have been really disappointed with headphones in general but especially IEMs. Apart from the Sennheiser HD580, I have never really heard any headphone or IEM that sounds convincing for classical in such a way that does not make me miss my old speaker-based systems. As far as IEMs go, almost all of the ones I have tried have sounded mediocre at best, but mostly horrible, especially those that contain two or more drivers (i.e Shure SE310, Shure SE425, Westone UM2). But the ER4S sounds about as close as I could reasonably expect to a small broadcast quality monitor loudspeaker such as the LS3/5A. The vastly improved bass over any other headphone / earphone I have heard is a huge relief, as I no longer have to whince at the bass bloat. They also seem to be more forgiving of mediocre recordings than I was expecting. I have purposely been listening to my poorer recordings today, and they all actually now sound quite good - with other headphones they have sounded poor to the point where I never really listened to them.
The only downsides to these excellent little monitors for the price are that they suffer the same shortcomings as a small broadcast monitor speaker does (i.e lack of overall scale) and they are not as comfortable as my other IEMs (CX300 and SE215). I am using the grey foam tips as they are the only ones in the package that work and are not uncomfortable, but my other IEMs are so comfortable I would not know I was wearing them (were it not for the isolation and music coming out of them). So I think I will try the Comply tips, but picking the right one is going to be trial and error I am afraid. I also notice that there is still a very slight low level hiss when connected to my XCan V8, despite the 100 ohm impedance and not being a highly sensitive IEM. Still, the hiss is far, far less than I was getting with my old noise cancelling PXC300. Whilst I certainly agree the cable is incredibly microphonic, luckily for me I am only using these for home listening with my desktop setup, so it isn't a problem.
Although I am really happy with the ER4S and I could say that my "search" is over, I will still buy others in the future, but for me the ER4S now sets some sort of benchmark and reference, since it really is the closest I have heard to a good small monitor speaker (and the HD580 the best I have heard compared to a medium or large speaker). I had reached a point of disillusionment with headphone sound in general such that I was contemplating selling all my headphone gear and saving up for an amplifier, speaker stands and a pair of LS3/5A speakers. But I think the ER4S has saved me from needing to take this very expensive step.
I would be really interested to see how my setup (XCan V8 with Mullard tubes plus ER4S) compares to the entry level portable Stax setup - they are worth about the same in dollar terms if you exclude the cost of my Mullard tubes. Another comparison I am interested in making is with the new Musical Fidelity EB50.
