Thanks for the heads up, but surprisingly pricey.
Transmission Line (TL) cabinet design doesn't get the attention it deserves IMO, especially now that Martin King has developed a MathCad application to finally provide a design tool. I've been listening to them since I discovered Irving M. (Bud) Fried's stuff in the 70's. The 8 inch woofers in 6 cu. ft. Fried TL cabinets I owned were spec'd to 114 dB at 17 Hz.
There are a few single driver/TL vendors out there, the best IMO is Bob Brines. For less half the price of the Sampan, Bob offers the same performance at 6 dB better efficiency in his FT1600 Mk II (and you can pick the veneer). High frequency "beaming" would start at 5,000 Hz instead of 10,000 Hz with the Sampan, but beaming can be a good thing.
My guess is that the circuit mentioned in the linked review is a combination baffle step compensation and zobel, like Brines uses. It's simply enough and much preferred to using it without or dealing with crossovers and differing drivers.
