Thats very kind of you. I still enjoy reading this as its definitely the most insightful and open minded thread i've found on headfi, but sadly having tried fruitlessly to find that elusive IEM that would give me the SQ i wanted without residual negative effects on my hearing, i temporarily gave up on headfi altogether and returned to 2 channel. To cut along story short i really missed listenig on headphones, so my ever persistent local shop keeper suggested i try closed backs. Initially unimpressed by what was on offer (i must have demo'd 15 pairs) i tried and enjoyed the Elegia and then Focal kindly launched the pocket emptying Stellia, which did just that and i was back in the game.
First thing i have to say with Feliks Audio, is whatever you do dont listen to the model above the one you can afford, i did and ended up bending my credit card with the Euforia. I've listened to pretty much all of their models and they all hit well above their price tag, but the Euforia is just whole other level, Its better than the Elise in every area of performance and i would say its one of those rare products, like most of the Qutest or Hugo2, in that its peerless at its price or even twice its price point. I listened to the Auris HA2 SE, which is a beautiful thing, but ultimately sounded souless by comparison. From and IEM listening point of view the Euforia is almost completely silent. I have listened to the EE ESRs and Grado Gr10e (my last remaining in ears) quite a bit and they sound really good even though they're rated outside its sensitivity range.
Re your question on double amping with the H2, i initially ran it feeding the Euforia in line level mode by pressing the XPHD filter button as i start the Hugo up. You only need to do this once and it remembers it. Subsequently i experimenting running it normally with variable volume control, mainly because the Euforia doesnt have a remote and it lives quite high up so as to save burns on tiny fingers and me from marital strife, but also because i have found enabling the DSP volume control in roon has a detrimental effect on SQ. Anyway after comparison i could not hear any negative effect on the SQ from running the Hugo2 and supposedly double amping. Worried about this i spoke to Chord and they reassured me that it effectively still preamping but with variable level. I did try my brothers Qutest for a week, and the inconveniences of no remote, having to use DSP Roon Volume control and not being able to use it as a portable amp by far out weighed inconveniences inherent in the H2's design, ie, micro usb and relatively tiny RCA connectors.
Two other quick things to note on the Euforia, first you can improve its already spectacular performance, for relatively little expense (£100-200) by swapping stock tubes out for EL38/E11 and second i would suggest budgeting for a good mains cable. I went the DIY route with outstanding results versus cost as i have done with RCA interconnects too, but thats a whole different depth and complexity of off topic rabbit hole, that i wont test everyone heres patience with any further