I find it more difficult to listen to the ER-4PT without the 4S adapter. The 4S adapter really does restore the clarity and the treble and bass are further extended with more even tonal balance through and through. I was listening to my AKG K 702 for a long time now to burn them in, but I feel like I'm missing out on the sound now that I'm listening to the ER-4PT/S combination. These are my most accurate IEMs and headphones for that matter. The K 702 are a very close second, but the ER-4PT/S is tops right now. I wish I had better full sized headphones, but I don't and I don't plan to get anything else until later this year during Black Friday or Christmas. I've heard a couple of top of the line UIEMs and none come as close as the ER-4S in terms of accuracy. It is very close to the Ultimate Ears Reference Monitors with the universal fit option that I tried last weekend in NYC. This is the kind of sound that I go for. Mine are my favorite headphones right now. These are near and dear to my heart and ears.
I find the ER-4S to be 92% accurate
The ER-4PT is 86% accurate
The AKG K 702 is about 80% accurate
For me, accuracy is defined by neutrality, clarity, and transparency along with resolution. The ER-4S is the closest to that definition. The ER-4PT is behind because it does not have extended trebles and there is a slight bass boost. There's also a loss in resolution. The K 702 has a softer and more polite neutral sound that is fairly accurate, but it is not nearly as realistic as the ER-4S. I feel like I'm only getting a portion of the accuracy when I listen to them. I think that they're good headphones, but I'm starting to notice the glaring differences. The ER-4S is more involving. It's got the accuracy nailed so the timbres and tonal balance are correct to my ears.
I don't like bass heavy headphones or earphones like the Monster Beats. They're not accurate from top to bottom. I think they are expensive too.
The ER-4S are better than my Ue-18 pro by a wide margin. The Ue-18 pro has problems with frequency incoherence and tonal imbalance as the dual bass woofer drivers are tuned up significantly to provide a more solid foundation to the music. They feel like I'm listening to subwoofers in my ears. On choral mass music, I can hear the disjointed irregularities especially during louder fortissimo sections. Everything gets stuck together like a big mess of incoherence. The ER-4S don't have that problem. They don't have the headroom of the Ue-18 pro, but I'd prefer a leaner sound that commits sins of omission rather than a fuller and richer sound that commits sins of commission.
I'll keep both of them for a few years, but I can easily reach for the ER-4S more frequently when I want to hear the truth in a recording.
Edited by Leslie Dorner - 3/18/13 at 8:56pm