Thanks all for your kind comments.
The subwoofer box is made from 1" MDF sandwiched to 0.5" Fiddleback Stringybark (an Australian Eucalypt species). The fiddleback is very strong, giving deep 3-D ripples, which the photos don't bring out that well.
I am using a Borbely All-FET crossover, 24dB slope at 100Hz, which feeds 2 x Stochino 100W monoblocks for the 1801s and an Aussieamplifiers (Anthony Holton) 200W NX150 monoblock to drive the Scan-Speak 23W sub. There is a unity gain buffer at then end of the filter, which I am changing to provide 6dB of gain to better match the inefficient sub with the 1801s (As a sidepoint, Erno Borbely is not only a great audio designer, but also a really nice guy who goes out of his way to help and offer advice)
The 1801 stands are veneered with Tasmanian Blackwood. but I can't take any credit for these, as they were built by a friend who is a furniture maker. I will take some more photos of the stands and post them tonight.