I just found a pair of demo Skylines for ~33% off, which put them close to the price of a pair of GIK D1 diffusion panels. I've been very interested in these 2D diffusors for quite some time, and I'll definitely be posting my observations to this forum.
I'd also love to try a set of Ethan's diffusors instead of the MiniTraps (HF model) on my rear wall. I like the idea of a combined bass trap and diffusor.
On another note, I think I might need more bass traps, especially on the ceiling / wall interaction points. While my speakers are line-source for the QR and ribbon, it seems that the bass radiates more vertically.
-- Nils
