My opinion on imaging in IEMs for gaming is quite strong : I say it really doesn't matter. For maximum competitive advantage, it's about a strong, obvious L/R separation which you get out of the box from almost any IEM. In the heat of the competitive moment it's that clear and blunt directional audio that makes the difference, as opposed to attempting to pinpoint things precisely. It sounds good in theory to be able to pinpoint things with good imaging, but in practice competitive FPS is too fast paced for that to have an impact. So as the guy above said, choose your IEM for it's musical benefits. I can confirm the Aria's directional audio was spot on for Apex.
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From @fluffyr