With 4 8545 and 1 R30 per side nominal impedance will be 8Ohms but there will be an efficiency mismatch from my calculations. 6 mids and a pair of R30's per channel give a lower nominal load and a 94dB sensitivity match if my calculations are right.

I've been diligently reading Jim Griffin's white paper the last couple days and any help would be appreciated.

Well initially amplifiers will be SS PS Audio Delta 100 stereo amps, 2x120W into 8 Ohm. I have 2 available so I could biamp them using my Behringer DCX2496, but I may eventually decide to build passive crossovers for them mounted on an external rear panel so I can just use one amp or possibly dual monoblocks, or a pair of Bryston Power Pac amps in the future. Not sure what the far future would hold for them but if I build them large enough the efficiency gain might lead me to use a valve amplifier. And then again there's also the possibility to go Class D or Tripath based amp down the road.

Looking more into the design I believe the proper way to go right now is to go full hog and get another set of ribbons to stack alongside the array.

The NFR crossover point is recommended at 1100-1200 Hz to match the 8545 woofers which begin to roll off at about 1100 Hz. Looking at these drivers in a 60" array at this crossover point would give me a rather short near field response, making my current listening position in the far field region.

Any thoughts on this amplifier setup to go with my DCX2496?

Also recently I've been having a hum issue with the Behringer which is feeding my Logans (biamp) and my subs. The sound only comes through the sub channels. I'm not quite sure if it's the XLR cable's at this point, the connectors or internal in the processor on those channels. Anyone ever come across this?

I've been looking at other digital crossovers but I can't cost justify the expense of the DEQx yet. Though it looks lovely in black