I bought mine only yesterday from Selfridges London, they told me they've had no returns so far. The serial number is with a 4...
Getting a seal is not easy (nothing JVC Spirals didn't sort out
since monitors themselves are quite on the small side, not unlike IE800, but a very different over the ear fit.
I would say that unlike IE800 that need no fiddling, finding the right tips with T8 is most essential and my suspicion is that's prime reason the mmcx connector failing alongside putting them on with pressure on the connector side,only handle them by the earpieces themselves. You need to find the tip size that would not sink inside too much , otherwise it gets uncomfortable and the connector gets a strain angle. Beyer's tips are supposed to be ergonomic, but i found them a little pain, theres no explanation which side to put them on, one being longer, but a little testing both sides finds the answer quick.
Once you find comfy fit, all your troubles are over and you can start enjoying an incredibly coherent, open, yet full sounding speaker with just the right amount of analytical and sweetness.
A more refined (less in your face) treble, wider soundstage , warm midbass rather than sub are main differences with IE800, in latter everything is closer, more intimate, more V shaped perhaps with emphasis on both ends, whereas T8 sounds more breathing , quite forward with fab wide and layered bass and definitely less fatiguing treble, tho thats a matter of taste since i have never found the treble on IE800 a problem, but you do hear a noticeable difference in the way the Senn and Beyer approached the dynamic driver tuning. T8 are a most musical and easy to enjoy all genres from opera and classical to dirtiest of electronica.
If anything, both are terribly capable iems, but IE800 sounds a little less refined because of that forward, shhhh kind of a character in the treble that has been a part of a dynamic's tuning for a while. T8 is probably the first dynamic driver i have heard that bridges the gap with BA's by sounding whistle clean and precise , but with all the benefits of a speaker like bass and general sound. Now, that in my book is a great achievement and well worth the asking price since all the countless BA's ive tried have been good and bad in some respects, but none has been an ultimately convincing afair, from Layla's super high priced dark sounding attempt to A12's transparent, super detailed monster, plus countless expensive totl more, i have to say IMHO there's in no reason to prefer a BA over Dynamic anymore and that is this Beyerdynamic T8iE here. Stunning!!!