This advice is pretty sound. With rare exception, this is best practice until you get into the range where headphones cost around $3K or more. Headphones reach their practical price limit well before speakers so that’s where it starts to make more sense to break this rule, at least for a first setup.
Yes. This does get confusing and IMO claims like “___ outperforms its price point” are way overused. Right now I can confidently name a grand total of 3 sub-$1K pieces that I know for sure punch above their weight: Senn 600/650/6xx, Beyer DT880 600 ohm, and Schiit Asgard 3. End of list. That doesn’t mean there aren’t other very good products under $1K that are also excellent values (that list is long!) but that those are the only ones that I can say with confidence truly have performance that belies their prices in the positive direction.
Thanks for clearing up the frequency questions above and this is where I think you’re likely just gonna have to take a buy-it-and-try-it approach. Based on your comments I’d consider the following:
option 1
Focal Elegia ($400), iFI Zen DAC V2 ($130), Schiit Asgard 3 ($199). The Elegia checks your boxes for isolation and spatial performance. In its stock tuning it does not check your boxes. However, it responds to EQ well, hence the Zen DAC recommendation, because the Zen’s bass boost is amazing, and when piped through a muscly amp like the Asgard 3 the Elegia’s bass can be a lot of fun and sound really good. You may still need to EQ down the frequency ranges you mentioned because the Elegia is a tad aggressive in those areas for some listeners.
There are two big drawbacks to this approach: 1) the availability of the Asgard 3. Schiit is very backed up right now (insert constipation joke here). If one is available, the Jotunheim 2 is a marginal upgrade from Asgard 3 but also costs $400. But…since you already spoke of upping your budget, you could look into a Lake People G111. I’d recommend that over the Singxer amp anytime. 2) If you don’t like the Elegia’s stock tuning and get tired of using EQ all the time (which can be a pain!) you might be stuck and have limited your options going forward, short of selling Elegia and getting a different headphone.
option 2
A headphone that checks just about all the boxes you’ve mentioned is another Focal, the Radiance (the one with Bentley’s name plastered on it for reasons that still don’t make a lot of sense). It’s bassy, warm, detailed, and has the spatial presentation you’re asking for. It’s also just shy of $1300 and will smash your current budget. That’s ok in the short term because it’s easy to drive. The little Fiio will power it fine for the time being. Down the road I’d save up some money and get an amp and dac for it. It will show you the benefits of good amps and dacs even moreso than Elegia will. I worry this headphone is too big a jump too fast and you may not recognize why it’s worth $1300 (which it absolutely is) and have some buyer’s remorse.
A final thought…it’s ok to say there isn’t one headphone that will do all you want it to do…especially with the budget you named. You can get a fun, bassy headphone for music (Meze 99 series, E-MU Teaks) and a more spatially exacting gaming headphone (DT880 600 ohm, if you can handle its semi-open design for gaming…but you must get a good amp for that one…Asgard 3 and G111 would still be my recs for it).
Good luck!