How would you guys characterize the sound with stock tips (please mention which) in terms of FR?
I think after months of listening to these almost every day I can kinda tell where they fall short in terms of tuning. It did occur to me early on that the mids are a bit strange and not as realistic as some Harman tuned headphones. For starters, the resonance peak at 2.7K sounds a bit off, well it's not so much the peak as the early rise to that peak. I'm hearing some warmth at 1K(ish) I think and then the high mids\low treble die a bit too quickly after that which leads me to the next issue. The treble is a tad too dark, the lower treble that is, which creates an odd contrast with the peaks coming at 10K and 15K, which are a bit boosted but not really harsh (well nothing like an HD600, which has terrible treble in my opinion by comparison).
I still love the tonal balance and the smoothness of the bass to mid to treble transitions but I don't think the FR is quite right. I'm eagerly waiting for a new flagship Etymotic to come out with even better tuning although I still think BAs have quite odd timbre\texture. It doesn't sound quite right despite being fairly quick drivers in terms of impulse response.
Never head the hd600 having terrible treble. In fact in my opinion it is one of the best there is and so close to perfect. In fact I just spent some money on a kameleon filter, which is awesome. It tones down the "very slight" presence bump in the treble. And flattens the sub bass and bass to insanely neutral levels. That's all. The hd600 does everything so well it only needs minor tweaks, but those tweaks make it unbeatable at almost any price range as far as I'm concerned (more than it was already unbeatable)... for headphones. For earphones on the other hand, etymotic is king for me.
I find that with the eartips, so much is dependent on depth and seal and vacuum and whatnot. Generally speaking the gray foam are on the brighter side for me, but I've had times where they are every bit as good as the silicone. It is just that generally, getting them to go as deep is very difficult, and that alters the response towards being bright.
The stock silicone tips, when deep and sealed without a vacuum, sound phenomenal to me. But sometimes I personally have trouble preventing a vacuum, as they seal so well, being inserted they build up pressure or cause suction as i adjust them. But I've found whetting them usually fixes this. They also tend to equalize pressure after simply using them for a long time. With a vacuum they tend to sound anemic. More mid centric. Not crisp and clear and not tight bass either.
The key for me is getting each tip to the best depth and seal. And for each person that is not the same. Some can't use grey foam to that depth at all. Some think they have a seal, butmay not or don't have the depth as well.
When everything is perfect the new er4 series has no 2khz issues for me at all, and I'm sensitive to that. The original er4s did, but even that I find is because they didn't work to fit my ear as well as the new models. The old tips I had were slightly different texture and never worked as well for me.
That's just my experience. Sure they aren't going to match everyone's target, but overall peaks and dips are incredibly minor with a good fit. Although, you may simply prefer a more harman target response, which is also very good.