Well, similar to the OP, am also a longtime lurker here - now first time poster, and proud owner of a pair of Layla's.
My first IEMs were Westone 4Rs. I then owned a pair of AKG 3003i's which blew me away, but were sadly stolen. And until yesterday, 846s were my day to day IEMs driven by an AK240.
Am in Hong Kong this week so popped into my favourite headphone shop after checking to see if they had the new Sirens in stock, which predictably they did. Have followed the reviews and feedback for JH Audio IEMs for a while - read the Roxanne impressions thread here from start to finish yesterday (where I learnt about the new sirens.... but managed to get no work done) - but wasn't left convinced. I know you have to try these things for yourself - but I get a lot of due-diligence insight by sampling the consensus view on head-fi.
I tried both Layla and Angie today - in that order - which was probably a mistake. To my ears, Layla appeared to be in a different class - and after just a few tracks with Angie - I had to put her down. I would love to be able to articulate exactly the difference - but I can't other than I know immediately a sound that impresses me and one that doesn't - especially back to back. I think it was the difference in clarity - but can't be sure. The difference was very clear to me though.
I listened in the shop to Layla for about 30mins - but the asking price made me nervous about making a mistake. So I did a deal where I could take the demo Layla home (paying for them in full) - and then get a refund tomorrow if they weren't to my liking, or swap them over for a new pair if they were.
Since being home, have managed to listen to them for an hour with absolutely all types of genre - from baroque classical to heavy metal and plenty of different types of vocals in-between. I am seriously impressed. The 846's simply - to these ears anyway - cannot hold a candle to Layla. I haven't listened to a single track that sounded better on the 846s so far. The 846's base seems overpowering (standard filter) and is clearly muddying the treble in my listening. The separation and clarity of Layla is clearly superior. But then it ought to be....
The treble I loved so much in my 3003i's seems to be present in Layla, but a little less forward - maybe missing a touch of their sparkle (from memory which is unreliable). But the 3003i's were lacking in base for my liking. Layla falls somewhere between them and the 846's in the base department (12 O'clock Layla setting) - which is exactly what I was looking for. So as far as I can tell given my short time with the demos - these may be the IEM's I have been hoping for but didn't expect to find.
Assuming my listening tonight goes well - I intend to swap these demos out for a new pair tomorrow. And happy to post further experiences along the break-in journey. Incidentally, the demo pair apparently only have a few hours of burn-in (3.5mm). The 2.5mm had no burn-in and sounded tight in brief comparison - so I will stick to the unbalanced cable for my assessment time. Plan on using the 2.5mm with my own pair though. All listening so far has been done on the AK240 with DSD or FLAC.
There goes my head-fi cherry.... love this place - have learnt so much from you all - thank you....