To actually comment on this thread, I’ve also gone through a lot of amps and dacs as well, can be pretty rewarding (especially in the higher end side of things). I’ve honestly developed a source gear first mentality with headphones in the past years (which I had for speakers for awhile, but I guess that didn’t translate to headphones for me until recently lol), cause if your source can’t get it right, doesn’t really matter what headphones you put at the end as they can only reproduce what they are given. Only am like that with higher end though, if I was working in the more budget to midrange side of things I’d much rather prioritize the headphones first over anything (since they tend to be less influenced by source gear, and cheaper source gear is more similar than different at this point).
That being said, there’s really so many potential pairings and combinations that it’s really hard to cover them all, and what might be appealing for someone may not for someone else, all depends on what you want to get out of the headphones and what you already have. Something else to consider with overall pairings and synergy is that your goal is the final result of the chain, so you really want to evaluate everything as one whole chain rather than evaluating something in isolation (if you can really do that in the first place). Basically just because something is great on specific chain doesn’t mean that same thing will be great on another, requires trial and error, and results will vary. There are a lot of great things that sometimes end up sounding pretty poor not because they are bad, but because they just aren’t properly paired.
At this point I think the headphones I’ve put the most time into figuring out what they work well with is the mysphere’s (3.1 and 3.2), to the point where I’ve likely gone overboard lol. Ended up making a personal pairing chart to document all the stuff I liked on a different forum, but I think with how important source can be with those headphones it was a worthwhile endeavor to really figure out how they reacted and what they were truly capable of in the end. (ended up liking the lampizator pacific → angstrom stella headphone mk2 for the 3.1 and totaldac d1-direct + d1-drivers mk2 → riviera aic-10 for the mysphere 3.2) But it does get tiring and there is a point where it really can become unnecessary/not worthwhile to try out all the potential pairings out there, generally if you find something you really like I’d just stick with that if you are satisfied for the most part. There’s always more options to try out there, but you don’t have to feel compelled to try everything (which is really easy to get caught up doing lol)
Not even sure how many amps I’ve gone through (guess I could pull up the spreadsheet and count but I don’t need another reminder of my poor financial decisions) let alone demoed, but I’ve been slimming down my collection of stuff to really suit my core headphones and ended up with a collection of stuff that I won’t really be selling and won’t really be that interested in hearing anything else to possibly replace them either (still want to slim down more though, but hard to bring myself to do that anymore atm). I did get caught up in sidegrading hell wanting to taste all the flavors per se but I think realizing I got caught up in that cycle was pretty important to really figuring out what I wanted and resting temptation of trying other things, and it’s been pretty valuable to consolidate everything down and not own source gear just for the sake of being different or having an alternative sound, instead picking something that encompassed the most of what I want with the right tradeoffs I was able to live with. It’s all a game of tradeoffs, there will always be problems or small nitpicks with pairings, but the goal is to find something where those issues are ones you don’t really care about. Not worth the time to find the “perfect” pairing since it’s likely a lost cause, just find something you enjoy and will be willing to live with