Hi JaZZ,
You might not have known that I made a few pairs of Float style headphones, and I really like them.
The soundstage and openness are marvelous.
Fascinating headphones, Wachara! I absolutely believe you that they sound great. Congratulations on such an achievement and to your designing skills! DIY electrostats! Yes, I know, the principle is quite simple, but the execution is another story. BTW, how is the (low-)bass reproduction with these two pairs, in view of phase cancellation?
So I get it, you absolutely appreciate openness, which equates to minimized near-field reflections. That's maybe my greatest concern with both speakers and headphones. Therefore my DIY attempts look a bit DIY, since maximum damping effect clashes with optimal aesthetics.
Transformerless ribbon supertweeter (active membrane size 8 x 25 mm)
Transformerless ribbon transducer, usable from 600 Hz up, in a two-way system (prototype stadium)
As you can see, the entire front surface is lined with absorbing textile (black velvet around tweeters). You barely see that on commercial speakers, and if, not in this noncompromizing form. B&W's Nautilus represents a speaker that isn't much dependent on front damping measures (since it renounces a classic baffle exactly for avoiding near-field reflections on it), although in my opinion the residual bare surfaces around the drivers, especially the tweeter, would benefit from them as well.
I'm not into speakers anymore since quite a while, but have modified two Stax headphones (Lambda Pro and Signature Pro drivers), animated by the Sigma. Primary goal was angled drivers, but with clearly smaller angles than the Sigma's: ~35° for the Lambda drivers, ~21° for the Signature drivers. Numbers and assignments are arbitrary, I just wanted to try different approaches.
Since they are meant to work on a sealed air cushion between drivers and ears, they need housings with reflective walls, so they won't sound as open as your two models, but in turn possibly offer better low-frequency extension. After all I've taken extreme care for inner damping, all bare surfaces are lined with pieces of carpet wrapped in black velvet. Sadly I couln't do the same with the stators... But just saying, even the wires serving as rear grilles had an audible impact, and not a good one, but I didn't want to renounce their protective function.
Marcel