This is my first review on Head-fi and till this day I do not possess the audio vocabulary that many others on this forum have and for that very reason, I will try to keep in simple here. This was at that point in time and still remains, my only foray into the higher-end universal IEM category and for various reasons I will mention in the review, it will likely remain for some time unless I someday find myself in the money.
Isolation and fit
I think I will start off by addressing some "misconceptions" that I believe exist about the IE8s and this more or less centres around fit issues that many people have complained about (though this may not apply to everyone). This in turn has caused a lot of them to feel that the IE8's isolation is poor. I tend to agree with this, but only to a point. Let me quantify my view because I do believe that with the right fit, isolation is possible albeit not 100%.
When attempting to achieve the right fit, this article "basic guide to in ear canal phones" is beneficial especially point 8 re: how to use your IEM; the link for this is: http://www.head-fi.org/wiki/basic-guide-to-in-ear-canalphones. But in a nutshell, when putting the IEM into my right ear, I use my left hand to pull the tip of my ear up and outwards ever so slightly and use my right ear to place the IEM in my ear canal and again, slowly, with a little screwdriver action, push it in. This has worked wonders for me especially with my current favoured tip.
Here is a picture of the tips I use after testing the other stock tips provided. I added the original tip just for reference more than anything else. For convenience, I'll just call them tip 1, 2 and 3 from the left to right respectively.
My favoured tip from the ensemble is tip 1. For a long time, I lived with the original tips and never liked the idea of switching from conventional tips partly due to stubborness and also the belief that I'm a normal person, but I was just in plain denial. For starters, everyone thinks I look like a 10 year old due to my small frame. I obviously didn't heed that warning and then there are other factors like my elongated face structure shaped like a papaya (paw-paw) in stark contrast to my small frame; but I'll save you from the other gory facts 
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All of us are born differently, have different ear canals, etc. Hence the reason for custom tips and earphones. So perhaps, what works for me, may not work for you, but I'd encourage you if you are having fit issues, to at the very least follow the guide hyper linked and try some of the stock tips given or other suggested ones by members here before giving up on the IE8s if you already have them in your possession.
Tip 2 gave me the best isolation and though without any music on, I could barely hear people around me with deep insertion and once the music was on, I really could not hear the buzz around me in any way whatsoever, but this does come with a little consequence on the sound quality (SQ) which I will go through in the next section.
Sound Quality (SQ)
I rarely if not never turn the bass knob to the maximum and usually maintain it between the minimum and the middle depending on which tip I utilise. As mentioned above, I first started out with the original tips i.e. tip 3 and then I moved on to tip 2 for better isolation, but I found that with this tip the bass would tend to colour the sound and SQ to me dropped. I also found treble to be lacking at this point and I would EQ treble into the IE8s though I don't do that anymore as I just turn the bass knob to the minimum and the colouration is not as significant.
Bear in mind that when using tip 2 for isolation, what happens is that the passageway for the sound to your ear canal is shortened and this for the lack of a better illustration is like having closed headphones to some extent. There is no room for the bass to "diffuse" and my theory is that this is the reason why it colours the sound.
The reason why I've ended up choosing tip 1 is simply because though I lost isolation where if I was in an extremely noisy area or along the road, I would have to turn up the sound, the treble still shines best to me with this tip choice. The treble is not over emphasised nor is it harsh on the ears and perhaps to some, it might lack the sparkle, but with this tip, to my ears, it's just right and non-fatiguing.
Overall, to me the IE8s have close to none or little microphonic issues. The IE8 impresses with vocal presentations and many friends who have sampled my pair have noted this same fact as well. Their sound staging is extremely impressive and for that very reason, it makes the musicality of the IE8s just that much more wonderful. It is for this very reason that it is engaging, exhilarating and enjoyable.
One of the selling points to me about the IE8s was their versatility in that I could adjust the bass to my liking though now more often than not, I leave it slightly below the middle. To me, my IE8s are used when I'm on the go, when I'm walking. And when I do that, I like to listen to popular music, electronic stuff, anything that keeps me moving, anything that keeps my mind entertained and my heart pumping. And this is where to me, the IE8s have hit home. They keep me thoroughly entertained, enthused and motivated with whatever music I throw at it.
To me, perhaps the IE8s may not be the most analytical pair of IEMs out there, but it's sound staging makes up for that. But like I said, if I'm on the go, I want a pair of IEMs that are fun and the IE8s provided it in spades. I don't want to be analysing music when I'm walking around. And even if I do, I do it when I'm sitting in a quiet area and again, with tip 1, I don't have a problem. Obviously, you'd have to look at the purpose of you getting the IEM.
I have not gone into any technical details and perhaps this may not help in making a decision on a pair of IEMs as I do not wish to make technical claims of it's bass extension, depth, accuracy of instruments without having been able to sample or test many of the other universal competitors in the price bracket. I did my research before plunging into this and I have not been disappointed. There are now competitors that are said to be better than the IE8s, but the Monster Turbines supposedly don't have as much depth in sound staging as the IE8s and this to me, is what I want to feel in my music. I want to be there, I want to be in it, at the centre of the action. That is musicality.
Note: I first started out with al-cheapo IEMs which I at that time thought was already a huge outlay, but seeing that I loved music so much, I thought I'd look into something else which is unfortunately or fortunately, how I stumbled across all this.
When I first listened to my IE8s, I thought "gosh...why in tootarkarmen's name revenge did I spend all that money on the IE8s?" It was only when I switched back to the al-cheapo's in relative comparison did I realise how much I was missing, how much more the IE8s were offering me. I think part of the reason for this is because I'm not musically trained.
Note: I have tested the JH-10/11/13s and honestly and possibly, because I didn't have the best setup with me then, the JHs just revealed way too much for my liking, but I will reserve my comments. Suffice to say, I enjoyed my IE8s. I'd still love to own a pair of proper customs one day, but hey, I've still a lot to learn here and if I had the time and the money, I certainly would put in a lot more effort into all this. I'm envious of many of you who have been able to have your own personal setups, beautiful rigs and all. I don't know if I will ever get there, but to me, I just want to enjoy my music. The technicalities are somewhat beyond me.
Design and Build Quality
Looks wise, this is not exactly, well, beautiful but I certainly believe that though the SM3 is touted to be better than the IE8s in every way, this is the one department that I firmly believe the IE8s win . The IE8s have lasted me the longest in contrast to other IEMs which have always had cable failures on me, albeit cheaper models, but I believe the consensus is that the IE8s have the best cable quality re: kevlar coated too! Maybe if someone fired a shot, the thin cable just might be able to save my life 
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The replaceable cable was a real plus point to me especially since I was afraid of the cable fraying on me both at the connection of the earphones and at the headphone jack but with the quality of their cable, a replacement might not be necessary. That being said, a replaceable cable adds to the longevity of the IE8s and this was important to me too, and if the supposed loss of a little SQ was traded in for this compared to other potentially better earphones, I'm more than happy to live with it cos' I'd rather save than to spend a gazillion more replacing the IEMs.
Final musings
All in all, the IE8s have provided me with everything I've wanted in an IE8 bar the aesthetics side of it. I'd be happy if this was my last and final IEM unless there was something leaps and bounds better than the IE8s. To me, any other universal IEM in the same price bracket is nothing but a side-grade, not an upgrade. Sure, maybe if I had the money to spend, I would test out different setups and I'd love to so I can give a better input regarding my audio experience to aid others in their journey, but I don't and am quite happy as it is, though donations are most welcome 
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Let me just say that I do not have a music background. I've done sound for my friends and stuff, I've been in radio and tv studios, but that is as far as it went. Looking back at it all, I wish I had put in more effort into music. It's what I love, what I enjoy and what is an ever-present in my life albeit the fact that my parents do not agree to it especially when I study.
I suffer from double-jointed fingers to an extent that when I bar a chord on any string instrument, when I play a chord, after a few minutes, there is a high chance that my fingers get stuck in the position and I have to manually pry them loose. I do wish I learned the drums, but the band already had a drummer, so I never did.
Just a last side track note, for those that think the IE8s are just crazy bass heavy, I have the k702s which are supposedly bass light. But honestly, I think the 702s are bass accurate and the IE8s just have a warmth and colouration to some extent, that just make them a whole load of fun. I enjoy both of them so how you interpret that is well, another thing altogether. Suffice to say that at home, I listen to a lot more jazz and instrument based music, but I still listen to popular music e.g. I'm listening to MJ's Smooth Criminal and Blood on the Dance Floor and trust me, they are fun on 702s as well. But I'll leave it as that.
Pardon me for the long post and the lack of depth in this review. I just thought that I'd give my own little input albeit not great nor as musically extensive as many others but I enjoyed the IE8s so much I thought I'd put in a little effort.
For whoever that gets to read this, remember, it is your ears, your love of the music that defines what phones you choose. Everyone has different ears, different sonic perceptions and for that, we will all always be somewhat divided in what IEMs are best. Just take a look at how different people like different genres of music.
I hope that your experience with the IE8s has been as enjoyable as mine, or if not, I hope you have found that pair that suits your purposes to give you that enjoyment that music was to be, entertainment and raw emotion.
