For the sake of simplicity and for a controlled testing environment, assume all other contributing factors e.g. sources, dac, amp, etc. are the same. We are just comparing the construct/quality of IEM to IEM, period. If we are doing a true comparison, not even cables or the fancifulness of their looks should be part of the equation. Cables are just an extension from the source to the IEM, simply for the sake of transmitting the audio signal because there is no direct connection between the two. Cables inherently introduce resistance and imperfection to the setup which reduces the quality of the sound. The shorter the better. This is just the same for interconnects. No one wants to use a super long interconnect cable even if you have tons of money to throw at it, no matter how high quality it is. It can never be better than a setup that does not use interconnect in the first place.
Let's not first involve the inherent difference in sound signatures from different IEMs which contribute to people's preference to certain types/synergy. Shall we just first say that we have 2x identical 1plus2 IEMs side by side, one with silver/gold/uber cable and the other using ASG-2's stock cable (or any cheap copper cable). How would the test comparison turn out? How much worse would the one with stock sound? I think this has been tested by Eke, so we all know the answer. This part is obvious that the silver/gold/uber cable will win hands down because its price is also exponentially much more than the stock cable.
Now for the next comparison, we have ASG-2 (or any of the top-tier IEMs) with stock vs 1plus2 using the same cheap stock cable. We want to know which is a better IEM, period. Do note that 1plus2 is considerably much more expensive than most other IEMs (even some of the top-tier custom versions), cable being part of the reason too. So when I say fair comparison, I mean subtract the extra money you have paid for the tralucent silver/gold or even the uber cable. Bring that 1plus2 down to the level of using normal cables vs another top-tier IEM using the same one. How much better is the 1plus2 now with such a setup compared to other top-tier IEMs?