Alrighty, this will be impressions of the A3 after about 3 days of use.
First, some things about me. I have extensive experience with Universal in ears, specifically Shures line (215, 425, 535 especially) and UE900s (newest version) along with a brief stint with TF10s. When it comes to Over ear comparisons, I own Sennheiser Hd 650s and ATH W5000s and those are my primary cans for home use. I primarily use in ears for stage use at my relatively large church and for music enjoyment on the side.
When it comes to tastes and such, I like to think of myself of being a somewhat entry level audiophile.. I cannot stress Entry Level enough. (don't have the money at the moment to be anything more than entry level lol) I listen to literally anything but newer country music. I am personally not a basshead at all. I enjoy relatively balanced sound and that's pretty much it, I just want to hear everything in the mix. Take all that I say as words from a relative amateur because i am by no means a professional; especially at describing the sound of headphones.
Alrighty that out of the way. This is my first trek into the ocean of Custom IEMs, and I have to say, so far its been pretty spectacular on all fronts. But really all you guys care about is sound quality so lets get to that. DISCLAIMER: I have gotten approximately 15 hours or so of use out of these but have let them burn in almost 100% of the time I haven't been using them so about 60 hours of burn-in so far.
Bass- The Bass on these things is just outstanding. It was quite awe-inspiring coming from the SE-535s because even though they have very very capable bass, they can't hold a candle to the sheer quality coming from these. How I would describe simply it is just straight up thick but not overbearing. They really just have clean sounding bass along with it sounding huge. For my tastes this is about the perfect amount of Bass. Not bloated at all, just clean and dynamic.
Mids- They aren't quite as lush as the Se535's but the mids are incredibly clear and are without a doubt of some of the highest quality. Despite them not being quite as lush sounding as the 535s, they do sound fairly more detailed, especially when concerning male vocals. Highly enjoyable.
Treble- I mentioned the TF10s in my bio as having a brief stint with them, and that is because of my treble sensitivity. I really just couldn't handle them or enjoy them. The A3s on the other hand are not sibilant in the slightest. Its really quite glorious. I do sense that there could be more extension, but it really is not a huge deal considering its only that one driver handling the entire treble range. The treble as a whole could be described as detailed but not harsh, quite smooth but not veiled.
Soundstage- Wow. That's really all that can be said. Its absolutely INSANE what these things can do when it comes to soundstage. My first test of them left me wanting more considering all the hype i had heard about these on the forums and such, but after some burn in and after about 8ish hours of use (approximate) IN THE EAR (to loosen the ADEL up) the soundstage really opened up. I would say that with the Auto Module it is approximately 65 to 70 percent as big as my HD650s, which is ridiculous considering those are an open back fullsize headphone.
This is all i can comment on so far, but overall i think you can tell that I'm incredibly pleased so far. Will Update more when i get further down the line. Hopefully this was helpful.