I'm a Speedotron shooter, and don't know much about Buff's line-up. Will the Einstein heads accept a Chimera speed ring, or must I purchase Buff modifiers?
They're calling the above a speedring, which it's not. You'd want to 2x check you're getting the item pictured, not described.
I hope the SP Studio Systems Balcar mount works better than their Profoto equivalent, which is too loose and falls off.
Check the diameter of the insert in your existing chimera ring. I know from experience that the linked SP Studio insert is smaller than most (5.5" diameter or so), and does not work in many of my speedrings.
Kacey enterprises now has some flat 6" inserts that allow the flash head to be positioned further into the modifier, and give more even coverage. I don't believe they are on his site yet, so you'd need to email him.
Edit: I understand the Kacey inserts may not fit Chimera rings either.
You can buy one of Buff's speedrings and you Chimera softboxes will work with them. I think their speed rings are about $30. I don't use his stuff anymore, but when I did, I used me Chimera softboxes with his speedring. This was for the Alien Bees line, BTW - I don't know if the speedrings are different for the Einsteins.
Yes, that thread is about the Kacey insert that I was referring to above. Later in the thread, someone comments that these inserts don't fit the Chimera rings.
I have three of these inserts, and they work well.