I'll put it this way. The OK1 is the only headphone I've ever used that can fool me into believing the audio I'm hearing is happening in real life, like some sound effect, talking, whatever. The OK1 isn't the flattest in response in this bunch. It's actually a little bright. However, it does several key things that seem to make it believable. It has a pretty linear dynamic range, great transparency, and great clarity of note. You don't get attracted to the bud itself as it's playing music. The stage starts in the head, but it extends without a perceivable end, it's like daydreaming for ears.
Quick comments as I listen and switch back and forth between these earphones:
IE8 - BIG space. The size you get from these is great, and you have a nice, outside of the head experience. I do think the less then flat frequency response does ruin what could be an awesome stage space. A skewed frequency response can skew the shape of this space. Some EQing could even out everything and give a more linear presentation. Also, there's only around 30 hours on this earphone so far, so I expect it to open up just a little bit more. I see potential, but the coloration gets in the way for me. The driver itself seems to be broadly capable where you can both get good depth and top end detail. It's just not as even across the spectrum as it maybe should be. With some music, it sounds good. With other music, it's just a little off. I'm going to give these more time to burn in and play with some EQing. I just got these earphones, so my impressions are very, very initial.
UM3X - This earphone keeps impressing me. The one thing it keeps doing as I listen to a variety of music and switch from other earphones to it is that it points out little details in the music that I don't hear with other earphones. I always keep hearing new pieces of music that I haven't noticed before. It's a tribute to the dynamic breadth of this earphone and sense of space in the stage presentation. I'll make a note for any UM3X users, the stock foam tip is a very bad choice for this earphone. It has this midbass hump that it adds and it sucks out a sizable portion of the highs and even some upper midrange. Switch to another tip immediately or these will really sound weird. These earphones remind me a lot of my OK1 buds. I sort of view them as the warmer version of my OK1s.
Triple.Fi 10 - I keep going back to these and view them just like I did with the ER4S. Balance, balance, balance. The frequency response is flat. The dynamic range is linear. It lacks some of the dynamic breadth really needed to make it stand out though, more of a laid back presentation then some of the other earphones here, and this does make it suffer some in terms of overall presentation. You really do need that bottomless and effortless energy to really recreate a big presentation. The treble is outstanding with this earphone, extending up very high, and without a perceivable limit. The low end is a little subtle for some, but it sounds full and extended. It does come down to fit a whole lot though. You need a good, tight seal to get the low end response and fit is a sticky issue with these with it's large body that quickly runs into the ear somewhere any way you try to insert the tip. A larger diameter, well conforming tip works better, or a long tip if you can find one that'll fit, just to hold the body out a little bit and allow for more insertion depth. Outside of fit, these are the most pleasant to listen to earphones of the bunch, non-fatiguing, even with some of the most extended highs of the bunch.
SA6 - I just picked these up to play with. It's an earphone that I always wanted to try out. It's not a bad IEM, a little outside of this field of top end IEMs, but for a midrange product, it fairs well. I initially went straight to Shure Olive tips. I was a little put off by the frequency response it had. I played with tips and got better results, but it never felt in its element. I ended up going back to the stock tips and primarily the small one. Then I shoved the sucker as far in my ear as possible. These really seem geared mainly for deep insertion, sort of like you'd have with any other IEM product running those tiny, black single flange tips. The stock tips end right at the end of the nozzle, and it seems acoustically geared for this. After I started listening to them this way, everything changed. The response evened out, and turned from awkward to fun. I ended up using no nozzle filter (treble++) and no rear adjuster, making it more IB then enclosure which offers a flatter, and well extended bass response(think bass++). With the deep insertion, overall presentation is warm and bassy(with a good seal). The best way I can describe it is is it's a better version of the V-Moda Vibe. You get a similar warm presentation, bassy response, but it fixes the muddiness of the Vibe and gives a cleaner, more detailed and articulate version. It really doesn't match these other earphones, but at a mid level price, they fit well, and the tuning really works well. I'd love to see a 2-way or 3-way universal from them following the same adjustment matra. I'd be really curious to see what they could do.
OK1 - I've had these the longest and are the best buds I've ever owned. Even after listening to these top tier IEMs, I can keep coming back to this bud and realize how truely good the OK1 is at reproduction. It does so many things so right, and it's very well balanced, great dynamic breadth and air, frequency response range, separation and locational cues. It's just a lot of good qualities rolled into one, small package. It's not perfect of course. It's a slightly bright and the treble can be a little harsh/sibilant with some music due to the higher frequency focus. Bass is good with these but not subwoofer extended. There's a good sense of warmth, bass note and impact energy. You hear most of the bass notes, but you're not going to get a full, reverberating experience. Instead is it clean and crisp and energetic and just strong enough relative to the mids and highs to not have the earphone sound anemic. The midrange and treble will impress over and over again, great air, sparkle, energy, and even the bass will impress with great energy, cleanliness, and speed.