With all due respect (and no offense intended), I was looking for a helpful, unbiased comparison from users who have owned both sets. From my research - other than the Adel technology - the A series appears to use the same BA drivers as the V series with some additional crossover/porting, and of course, the new 3D printing for the shells.
Hi,
I own the V8 and the U12, and even though the driver configuration is different (obviously the V8 sounds warmer and the U12 is more neutral), I can still hear a similar house sound from the two earphones as well as the V6 I used to own (e.g. they all have a slight dip in the upper mids). I would agree with voicemaster that the sound signature of a V-series models and its A-series equivalent will not be very far off.
The V8 has very good soundstage (I prefer it over my K10U), but the U12 provides an open feeling unlike any other IEM I've heard (though I haven't heard the Layla yet). The U12 does NOT sound as open as my full-sized headphones (I only have the K7XX, Q701 and AD2kX).
My ears don't really get fatigued from non-sibilant IEMs (I listen at low volume levels and am in my early 20s if it makes any difference), but my ears do feel more relaxed when I listen to the U12, so imo the ADEL technology does work well.
However, I don't really know if ADEL makes things louder at the same volume levels, since impedance varies between different earphones. My Supra II is "louder" than my U12 at the same volume level, and the innerfidelity review says the Legend R is even more sensitive than the Supra II.
Unfortunately I can't help you in regards to isolation since you're asking about the A-series. My U12 isolates less than many of my IEMs, but I think it's mainly because the fit is shallower due to the large and sharp nozzles.
For stage use, I would recommend waiting for the manual module (or even the signature module) over the auto module (which I've read is similar to the manual module set around 70% open).
Would I pay $500USD more for ADEL? Yes, only because I trust that the ADEL technology will prevent (or a least minimize) hearing loss. It's a long term investment that I feel is worth the money. With that being said, I have to confess that I still listen to my other IEMs as much as my U12
