Hey Steve. Glad to see you taking the DIY plunge. I think starting with the two nearfileds is a good idea. As long as you are aware they will dominate the SVSs in every conceivable fashion. So, you may want to consider taking the SVSs out of the equation. But, you won't really know until you get the UM18s into the mix. Also, why 18 vs the 15s we were talking about at Richs house? Bigger is better, just curious as to why?
Also, the balanced mini is a good idea. You'll need balanced to RCAs for your recevier (don't buy any, I have 7; you're more than welcome to all or a few of them). Do you currently have a mic and REW? If not, I would recommend picking one up and learning REW. Only then will you be able to properly integrate the 18s.
As for the LCR. Is there a reason for the 893 vs the 1099? The efficiency of the 1099 would be worth the little bit extra they cost; especially if your driving them off a receiver.
HT: Oppo UHD-203 | Crown Amps | NX3000D | NX6000D | 1299s | Volt 8s | THTs | Crowson Shadow 8s | BOSS riser | Panamax 5300PM | LG OLED 65B6P
Family: Denon AVR-S740 | PSB Alpha AVs | Sony X900F | X1