I was having a coffee session with Randius abt two weeks ago, had an opportunity to try the AT-HDC5 cables I imported in for him (I was already using one on my own pair of IM02's since mid-March) on his pair of IM03's. I did not try out very demanding genres such as Orchestral/Chamber music, or any well-known japanese OSTs I am familiar with.
However, I did try with a couple of vocals tracks from Adele/JUJU, both vocalists which have very well-recorded engineered tracks by their studio labels and IMO, I really do believe after listening for myself the pairing of the AT-HDC5 cables really did managed to improve the overall sound quality of the IM03's by quite a considerable margin which is IMHO worthy of the cable's RRP. (personally for me I got these cables from Japan awhile ago at ard SGD 118 non-inclusive of shipping charges, but you should be able to get them locally via store retailers such as frn Stereo, Soundwaves or E1 @SGD 98.00 once AT SEA's distributors have their stocks in frm my understanding)
Most notably, I feel that not only the bass texture/clarity from the IM03 has improved considerably by quite abit, I also felt that the overall treble presence was not as warm/dark and extension also has some improvements compared to what it used to sound like when I tried those IM03's in stock form back during my audition session at E1. While the IM03 is not considered dark sounding by any means, it is still considered relatively darker in terms of treble presence when comparing to other models from AT family such as the IM02/CK100PRO, although in terms of overall sound sig according to the japanese AT engineers I have came across in one of my japanese audio magazine interviews, the IM03's are indeed acknowledged by the engineers as the spiritual successor model to the previous CK100PRO model released back in 2011 actually.
The AT-HDC5 cables should be a relatively good investment for yr pair of IM03's, make no mistake abt it. Rather than spending SGD 1,399 on a pair of Noble Audio N6's, which is more than x2 the pricing of a pair of brand new IM03 locally here, I would say it's probably a better idea for you to get hold of a pair of AT-HDC5 cables as an upgrade, as well as looking for a better DAP source for yourself. More often than not, I find that once you reached the lvl of owning stuffs such as CK100PRO/IM03, any further upgrades are really just a pursue of a different kind of sound sig for yourself, or just something that provides some diminishing returns in terms of overall SQ upgrades. Are you and yr wallet ready for something like that after forking out 1399? That is perhaps something you have to truly ask yourself.
I own quite a few TOTL universals apart from the usual ATH's myself, just check my Head-fi profile. Personally for me I have found that in terms of my own audio journey, to be able to own or listen to some other expensive earphones or TOTL custom monitors does not exactly represent or immediately bringing oneself to attain a higher level of aural experience. Of course in audiophile/gearhead speak, in many instances you will get an ego boost as well as bragging rights for having new toys. But most often than not, you will find that you are just actually pursuing this hobby in a different direction, having just obtain another 'different' sound sig in terms of presentation you have found yourself to be unfamiliar with previous, and you just got the chance to get yourself more acquainted with it at this moment after purchasing a new TOTL universal or customs.
With something of a level of the IM03, in my own words please do yourself a favour here. Although I'm not sure what current DAP source you are using it with these IEMs, but I have found that in my instances having an upgrade in terms of portable or desktop source, will reveal to you simply just how much potential behind you have not unlocked yet in terms of those IM03's. True story bro.
