As a friendly announcement, we've had a few users (who elected to use Type E tips) report to us the LUNA sometimes sounding "tinny with faraway vocals" on one side. It has sometimes led to quite a bit of alarm for some people, especially when they've only had their shiny new flagship for a couple of days.
We worked with these users to troubleshoot, and from preliminary experience of a small sample size of users, it is a fully reversible effect of the very soft surround reversing its physical configuration under a very tight seal. Please bear in mind that this effect may not be exclusive to Type E tips and is more a side effect of too tight a seal within the ear, stemming from the choice of ear tip, the depth of insertion, and the size of the user's ear canal. The more airtight the seal, the deeper the insertion, and smaller the ear canal, the less there is air for the driver to move, and if the LUNA gets pushed into the ear too quickly, most of that air gets evacuated, producing a vacuum seal in the remaining space of the ear canal, and affecting driver excursion. Luckily, this effect almost always reverses itself spontaneously (the polyurethane surround will pop back into shape from its deformed position), but to hasten its recovery, we've tried to get users to pull back on that vacuum seal really quickly before breaking seal. It sometimes takes a few tries to do, but has not failed to produce a positive result so far.
Please also bear in mind that most individuals will not experience this effect. As mentioned, out of the multitudes of LUNA customers that we have corresponded with, only a couple have reported this occurrence. Our engineer Andy is aware of this effect and we've arranged to exchange a unit from one of our customers to examine whether this effect only occurs due to unit-to-unit variations, but our current understanding tells us this is a user-specific issue pertaining more to seal and vacuum issues. From a macro perspective, we're fairly satisfied with our QC efforts so far, and we're getting within a half dB tolerance between sides. However, if you experience such an occurrence, please do contact us, via PM, or e-mail. We will work with you to resolve any issues you may encounter.