Well they have reviewed a BK Gemini II in the past, so WHF are obviously aware of such products, and also stuff like the infamous Gotham cable and the Beresford DAC ,so it's not as if they are completely ignoring cottage industry/direct from manufacturer products or whatever else you choose to call them and i'm sure there are other products also but those 3 sprung to mind.
It's also been mentioned by WHF staffers on several occasions, that they have a limited budget to buy products in for testing.So i guess are somewhat reliant on manufacturers supplying them the product's for test and maybe kit like the BK Monolith just hasn't been offered up by the manufacturers.
Pioneer PDP-LX5090/BDP-LX71,Humax HDR/9300T,AB-IPBox,Mac Mini,Beresford Caiman,Roksan Kandy MKIII,Arcam AV9/P7,PMC FB1i/TB2M-Ci/DB1i,BK Monolith DF,Chord cables,Tacima CS929