once I get my ck10s back, I'll be able to compare and review the im-02s.
For now, have a nice read on the comparison between the ck100pro and the im-02s from the hardware forums.
read the quoted post.
There is a comment that the im-03s are the successor of the ck100pros.
They are basically the same thing, but a bit improved and refined.
im-04 is entirely different from At's original ba lineup.
If you meant a comparison between the im-50s and im-70s, then I wish I could tell you, but maybe this forum might have information you are looking for.
Just cross-posting the short review I wrote for the ATH-IM02's from one of my local forums HardwareZone, over here since I see there have been some active discussions about the current IM balanced armature series in terms of Audio-technica's latest wave of releases. My pair of ATH-IM02's has been burnt in for at least 80 hours prior before I wrote the following review, as I got these sometime last year shortly after Christmas Day but since I'm more of a lurker and infrequent Head-fi poster, thus I was quite late in contributing my own impressions/findings about them.
I will not be A/Bing them against the CK100 as both models bear quite abit of different signature/SQ traits to them, but I personally do consider the ATH-IM02's to be a considerable good upgrade over the CK10. (despite both of them are similarly based on dual-drivers BA)
The ATH-CK100PRO was the previous BA line-up flagship model from Audio-technica, before the current IM series were being introduced. The CK100PRO's can often be misunderstood by many people especially if the listener has only listened to it only for a short amt of time, which also further implicate matters if you do not have the correct or pairing synergy of DAP/portable AMP as this ATH iem does suffer quite abit from acoustic/electrical damping issues due to the OI factor (output impedance) from various DAPs found on the current market. After some experimentation and findings via some taiwanese owners as well as my own, this issue can typically be fixed by using an additional impedance adapter (anywhere btw 30 ohms to 75 ohms depending on the OI of your player) btw the DAP and the iems, and it should solve the electrical damping issues of the CK100PRO, and gives it a more smoother response across the whole FR spectrum, w/o too much peaks around the upper-mids/lower treble regions.
Via my current Sony Walkman Z/TTVJ Slim combo setup it sounds quite alright to my ears, but is definitely not the most euphonic sounding pair of iems under my current possession. Best portable combo setups I have tried with the CK100PRO so far, were combinations such as the iPod Classic 5.5G + Centrance Hifi-M8 and an iPhone 4S + Fostex HP-P1. Single DAP setups that I have tried that sounds quite good to me were via the Astell & Kern AK120 and my previous older Sony Walkman the NW-HD5 which I still own today.
The overall signature of the CK100PRO's lies more on the aggressive, dry side of things and thus are not the most euphonic or musically-involving pair of iems that would invoke emotions easily when listening to vocals/acoustic stuffs with them. It is however a very revealing iem as reviewed/concured by another fellow Head-fier [URL="http://www.head-fi.org/t/687962/asg-2-ck100pro-ue900-and-fa-4e-xb-reviews-the-dysfunctional-family"]MoonYeol[/URL], so if you are someone who appreciates iem trait characteristics of highly-resolving detail and excellent clarity/transparency and you are a lover of genres such as classicals/orchestras, you owe it to yourself to at least listen to this pair of iems for yourself.
With the ATH-IM02 now in the picture, I consider the two family sibling members to complement each other quite well actualy. While the CK100PRO soundstage properties are quite abit more expansive, immersive and holographic to my ears, I personally think the IM02 is not too far behind either and has very decent depth/width properties. In terms of overall resolution/detail, the CK100PRO however does it better as it is extremely resolving at both low and high frequencies, as both its bass and treble texture are astoundingly detailed and other well-known TOTL universals on the market which have quad-drivers implemented in them such as the W4R/UE900 are no match against the CK100PRO's. (which another fellow headifer [URL="http://www.head-fi.org/t/585007/review-ck100pro-unboxing-impressions-a-retrospective-journey-with-audio-technica-and-versus-ck100/135#post_9650700"]a_recording[/URL] who has done many IEM/headphone reviews for the community agrees with me)
However, the ATH-IM02 do have some very good redeeming qualities to themselves and still manages to put up a pretty solid fight against the CK100PRO. IMO the ATH-IM02 are a much better vocal performer/specialist here, it possess a very nice midrange presence and its treble is of very good quality as well. (percussive instruments such as cymbals will not sound dead/rolled-off in short, as it has good sparkle and bite to it).
The ATH-IM02's are quite a pair of euphonic-sounding iems to my ears and they don't exactly bear any weakness when it comes down to either male or female vocalists (which cannot be said the same for the CK100 non-PRO model). In terms of sub-bass impact/rumble quality I also seemed to have noticed it performs quite abit more favourably to my ears against the rest of the CK100PRO/CK100/CK10 line-up respectively. (take note bass impact/rumble details are not to be mixed up with bass texture/resolution so do not be confused and mix them up)
I should however mention in terms of cables microphonic level/wearing comfort wise, it is indeed a tier lower compared to relatively well-known AT IEM's around the community here such as the CK100/CK10 models which was concured by another fellow Head-fier who is from my country as well, known as Randius on Head-fi. Owners will definitely encounter some microphonic issues with these, and in terms of wearing comfort they certainly do not compare that favourably against the previous CK10 as well. If you have never had any usage experience with either the CK100 or CK10, then this might not bother you so much but coming from previous AT flagship models like the CK100/CK10, I have to personally bring up this and admit that in this area, the AT-IM02 disappoints alittle here.
At the current street pricing that these are retailing at, I do not see why anyone wouldn't be attracted by the IM02's even when comparing these to new heavyweights on the market such as the Westone's W20 or even the popular Shure's SE535 LTD Red edition that are known to be good with vocal genres. I would highly recommend these iems to anyone who are looking for something to listen to male/female vocals with, especially with their high C/P value tagged to it.
The ATH-IM02 gets the highly recommended, thumb of approval from me. Do check them out soon, and of course sorry about your wallet too if you do manage to take the plunge into these!