To know whether IC's (or cables in general) are transparent or not is simply to compare the sound of your system with a live performance. This is not easy to do since audio memory is very short. But if you have gone to many live performances it makes it a little easier since you know what you are looking for in terms of sound.
Uh, well, yeah. I guess.
But IMHO it's asking a bit much of a signal transfer wire to bear the responsibility of recreating a "performance", live or not.
Odd how "the high end" has rejected tone controls while embracing a far more complex way of doing the same thing...a way that, unlike tone adjustments in the hardware, does not allow the listener to compensate as may be required, recording-by-recording.
In interconnects, I now look for the lowest capacitance and the highest build quality. And I can usually find it at far below the starting price of most "audiophile" brands (many of which have an oddly high capacitance, suggesting the 'tone control' aspect as a matter of simple math).
If your system is great (however you may define "great"), interconnects are a way of making it greater. If your system sucks...
you get the concept.
