Received them at my workplace, I was using my UM Mage before I popped in the 8X, so I can only compare them with the Mage. The first impression of the 8X is... hm... rather complicated...
I'm no good at writing this kinda things so bare with me, my portable rig is Sansa Fuze>LOD>RSA Shadow.
First, the sound is much bigger on the Mage, 8X appears to sound like a much smaller speakers, despite a very detailed one.
The 8X's focus is definately on the mids, particularly upper mids. Mids are also forwarded as many have described, and also very fast. Vocals stands out alot in tracks, but because the upper mid focused, some times vocals appears overly bright and a bit thin.
Treble extension is very good and very energized, although a little grainy. I'd say its almost at the edge of being sibilant because on certrain tracks it almost starting to sound harsh to me.
Bass is as advertised, flat, and fast. Quantity is just right to compliment with the mids, goes quite low too, bass never smears to the mids, which is good.
Instrument seperation is ok, Mage definately still has the upper hand here.
For the shell finishing, it's pretty fine. Some tiny bubbles spotted. The monitors sit too much inside the ear, with the cable plugs actually pushing my ear. I prefer a flush or slightly extruding monitor for comfort and ease of wearing and removing. Unique Melody is a master here in terms of craftsmanship.
Maybe I should give abit more time to it before drawing conclusion, but for now, I still prefer my old UM Mage due to the way bigger sound, better seperation and more organic decay. The 8X has potential though, will put it to burn in and see if there's any sound changes, although I doubt it will improve much.
Looks like my CIEM search is still long way...
This is exactly what I felt when I first received my AUD-5X. I was kind of disappointed with my CIEM because it was sibilant and caused me headache. I have asked Mitch to retune my 5X but it came out that I received a 5X with the same tuning. Hopefully you will get your 8X retuned successfully Good luck