I’d highly recommend these Hifiman Arya Organics that can easily be returned through Amazon if they don’t work out. I own the Arya Stealths that are a model below these and am thrilled with them, and the Organics are supposed to be a significant improvement (see review below) but aren’t much more expensive and still within your budget. They are also relatively easy to drive so should work perfectly fine with your Aethos. The Stealths are very open sounding with an expansive soundstage and imaging that is very much of an “outside the head” type of presentation. They are neutral and very balanced with great detail and tone with very quick, tight, and tuneful bass and are very light and comfortable to wear for long periods of time. They go quite low but don’t do boom boom kinda bass so if you listen to EDM, rap, etc. there are probably better choices, but if you want a well-balanced, audiophile experience these are excellent and very well worth a try. Just one idea FWIW, and best of luck.
The review…
https://soundnews.net/reviews/headphones/hifiman-arya-organic-review-comparison/