I've not heard the SR1a headphones yet; I'm waiting to do that before making my "end game" purchase. As a stop-gap measure, right now I'm listening to the Ether2 headphones, powered by a Pass Labs HPA-1 amplifier (both purchased near-new (so, "used")).
I demo-ed the MySphere 3.2 headphones in the Fall and they are spectacular. For almost all well-recorded music of the genres most audiophiles listen to, I don't think any person who already has an amplifier they really like would regret buying and listening to the MySpheres for a long time. If 90% of one's listening is to techno-pop or electronica or some other bass-heavy genre, surely that person already realizes an open ear headphone is not going to satisfy. If you don't have a room isolated from outside noise, or others don't want to listen to what you're listening to, then this style headphone isn't what you need either (but then neither are most open-backed planer or dynamic headphones). But in a quiet space, with almost all well-recorded music, the MySpheres are wonderful and (nearly) without peer. I've never heard anything so satisfying and relaxing.
I was thinking of purchasing an Apex Teton early last year; had I invested $5K in a really nice tube-based amplifier then, I would have purchased the MySpheres immediately after (breaking them in for 100 hours and) listening to them - and never looked back. If I don't go the Raal route, and it's quite possible I won't, a Teton plus MySpheres is what will reside in my Study before the end of this year.
PS The MySpheres "fit" differently. After figuring out how to put them on and adjust them for comfort (because there are a couple of variables for how one wears them) almost everyone becomes happy with the fit and only concentrates on the wonderful delivery of music. It's like driving a "better" car (Mercedes, BMW, Volvo) that is "different"; once you get used to their design/ergonomics you find you actually like them better. For those few who can't get comfortable, Heinz (owner/designer?) says they offer an option for custom fitting. Keep an open mind for the first week of listening; after that time most people have long forgotten about how the MySpheres fit.