It has improved a lot over the last two or so hours, and is now barely perceptible (I'd guess ~1dB?). I'm gonna run them in for a bit longer but I'm thinking it is the fabric damping issue and I will cut a hole in the other side to match to see if that's the problem.
I'm going to use the cliched bumblebee analogy in describing its speed... it doesn't know it can't go that fast, which is how it does. Really really fast. Listening to 15 Steps (Radiohead) and The Creator Has a Mastertape (Porcupine Tree) is an experience. It is slightly bright so you may not like it too much. And yes, once I find my stash of WPI jacks and plugs I will make the SR-X Pro and let you know. I'll look again today, but some places in my house are quite a bit of a mess.