My initial impressions:
I find that initial impressions are always good because your ears are hearing it for the first time, fresh, unbiased. Later you get used to something and your perception changes.
No hiss at all from Fostex HP-P1, first bit of relief.
Firstly the cable, as strong as it is, is inadequate IMO. Mids sounded veiled and micro details were less than recabled SRH940 which surprised me initially, left me scratching my head. Swapped to Toxic Cable Silver plated copper and noticeably more bass but i felt that slight mid veil was still there so swapped out to Toxic Cable Silver Poison pure silver cable. much better. Excellent synergy. Nothing is lacking in bass, mids veil lifted, micro details veil lifted. Now i know why everyone was talking about TWag which is also a silver cable. Yes definately worthy upgrade on my setup, YMMV. From this setup is where I started to critically analyse the ES5s.
Fit is actually almost perfect. Comfort is high, soft tips really aren't just marketing gimmick, they are truly comfy and isolation is the best I've ever experienced, even better than P series comply foams, and they are very good already. Can truly listen at lower volumes, but also because bass is good and mids not rolled off so no need to pump up volume to compensate.
It's still very early days yet (6 hours) but initially the bass is much more than SE535ltd, and SRH940. Actually come to think of it the SRH940 with cable upgrade is a decent performer in the bass department, contrary to what others say. It's accurate, tight and not over stated. ES5 has slight bass hump and performs as well as DT1350 tesla driver without the funky timbre issues. Punch, extension and amount is all there and satisfying but it cannot slam like a 50mm driver can physically (move whole ear) but it does a pretty convincing job. Bass not as slamming as Edition 8, but ES5 has bass texture: different levels, different flavours, rumble, growl to gravelly crunch to sythesised snap. Double bass is chunky and not just a blob of bass. Its not lacking in anyway at all, very good balance, very satisfying.
Micro details are all there, nothing missing. SRH940 does good job of this too but ES5 does a better job with upper mids and highs. Maracas and cymbals seem more prominent, clear and crisp than before in tracks I've heard 100 times. In fact upper mid to high instrument separation is superb. Some tracks astoundingly good. As cliche as it sounds, I never thought I'd hear anymore after SRH940 but I am hearing new things on tracks I've heard 100 times, honestly. Astounding.
Now most important to last, mids and vocals. Shure products have more forward vocals that is for certain. Es5 not recessed by any means but not as in your face forward as Shure, will take time to get used to it. But mids on es5 are full, lush, crisp and creamy. Guitar pluck is so lifelike, note decay so realistic. Piano reverb inside wooden cabinet. Harp string pluck and reverb very lifelike. Miles ahead of 535, much more lush and full than 940, more realistic than DT1350.
Voices are superb. Complete, full, nothing lacking at all. Captivating. Stop typing just to listen.
Soundstage nothing to write home about. It's good but it's as good as an iem can get, which is nowhere near floorstanding speakers obviously (I've heard some of the best money can buy so have a high bar). Maybe not as convincing as S logic on edition 8, but don't get me wrong, nothing inadequate, just nothing spectacular either. Still need to use imagination, unlike floorstanders. Better than any iem I've heard so far though, some tracks much better than others obviously.
In the end, worth it! This is what I expected from es5 and I am not at all disappointed. Far from it I am satisfied and relieved that I made a totally blind $$$$ purchase and it turned out great. They remind me of the Fitear Private C435s that i demoed, which is a good thing. I don't feel the urge anymore to look into other customs or those FitEar 334s. These are superb and end game for me as least for the next few years. Come to think of it, it's a relative bargain all things considered!