My 2nd hand but like new ASG-2.5 just touched down this afternoon, listening to it right now while I am writing this post.
Fitting: 20/10 (not a typo!) well I thought Westone are comfort, not until today I laid my hands on ASG, man I
TOTALLY can't feel it on my ears even if I try to! This is how dam good it feels around my ears!
Build: 8/10 cosmetics wise
you can't compare it with Japanese craftsmanship, that being said, it still acceptable and you can definitely tell each pair is individually hand-made and hand-polished cause you you can easily see difference between L & R side. Gives you kinda typical American raw feeling.
Accessories: 8/10 Pretty standard stuff, nothing to mention or worry about. Comes with few pair silicone double and singles tips. I rolled a few different tips since the stock one doesn't sound very good, actually sound become a bit too thick, until I put on some old UE tips then it starts revealing a lot more details.
Sound signature: Mind you this is purely my personal thoughts, bare in mind we all hear differently plus I am sure mine is NOT burn-in. Still listening, paired it with DX100 & Aune T1 (tube DAC as shown above). In general, it sounds dark, warm & thick but not muddy. Moderate pacing, definitely not a fast type (even when I am listening to MJ). For those who used to analytical details like from multiple BA types of phone, I wouldn't recommend ASG-2.5. My DX100 doesn't seems sufficient to drive it well even I set it on high gain and I am using it on my T1 with 10+ gain. Over all it sounds identical to my Philips X1 (I know I shouldn't compare it full size cans but that's the best way how I describe it). As I've been listened to it for 3-4 hours now, you can tell the sound is not fatigue at all.
Bass (port closed): 9/10 Sub bass well extended and deep with texture, not muddy (even on a tube DAC!) mid bass wise nothing really specific to mention. Overall I can't hear any bass bleeding into the mids of highs.
Mids/vocals: 7.5 ~ 8/10 quite smooth, neither recess or forward, sort of in the middle to me (unlike Westone UM Pro 50, really really forward). So far I haven't experience anything really touching or merit in regards to the mids, thats why I score it a bit low, not necessary means the ASG-2.5 is not good, plus remember it's not run-in. Besides, quality of the mids vary from song to song, think I need to follow this up later.
Treble: 8 ~ 8.5/10 Better than I expect, not sure how it compare to ASG-2 as I never try it, ASG-2.5 possibly a little bit roll off in this regards & I prefer the treble from my UE TF10(with Oyaide cable). Still, the highs are airy enough when comparing with many other cans. Another good thing is there isn't any hiss or harsh shouty highs that I come across with yet (and I don't think it will).
Soundstage: 8.5 ~ 9/10 Quite wide for an iem, reasonably spacious but not extremely wide. Definitely good enough for chamber music and classical. Somehow and sometimes notes are well extended so as the soundstage. Layers are there but not discreted, smooth transition across all frequencies (people call this intimately??).
Hope this help, I might update my comment in a week or two.